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Sample records for scd4-17b bifunctional protein

  1. Clinical and biochemical spectrum of D-bifunctional protein deficiency

    NARCIS (Netherlands)

    Ferdinandusse, S; Denis, S; Mooyer, PAW; Dekker, C; Duran, M; Soorani Yancheshmeh - Lunsing, Roelineke; Boltshauser, E; Macaya, A; Gartner, J; Majoie, CBLM; Barth, PG; Wanders, RJA; Poll-The, BT

    Objective D-bifunctional protein deficiency is an autosomal recessive inborn error of peroxisomal fatty acid oxidation. Although case reports and small series of patients have been published, these do not give a complete and balanced picture of the clinical and biochemical spectrum associated with

  2. A conserved regulatory mechanism in bifunctional biotin protein ligases.

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    Wang, Jingheng; Beckett, Dorothy

    2017-08-01

    Class II bifunctional biotin protein ligases (BirA), which catalyze post-translational biotinylation and repress transcription initiation, are broadly distributed in eubacteria and archaea. However, it is unclear if these proteins all share the same molecular mechanism of transcription regulation. In Escherichia coli the corepressor biotinoyl-5'-AMP (bio-5'-AMP), which is also the intermediate in biotin transfer, promotes operator binding and resulting transcription repression by enhancing BirA dimerization. Like E. coli BirA (EcBirA), Staphylococcus aureus, and Bacillus subtilis BirA (Sa and BsBirA) repress transcription in vivo in a biotin-dependent manner. In this work, sedimentation equilibrium measurements were performed to investigate the molecular basis of this biotin-responsive transcription regulation. The results reveal that, as observed for EcBirA, Sa, and BsBirA dimerization reactions are significantly enhanced by bio-5'-AMP binding. Thus, the molecular mechanism of the Biotin Regulatory System is conserved in the biotin repressors from these three organisms. © 2017 The Protein Society.

  3. Evidence for increased oxidative stress in peroxisomal D-bifunctional protein deficiency

    NARCIS (Netherlands)

    Ferdinandusse, Sacha; Finckh, Barbara; de Hingh, Yvette C.; Stroomer, Lida E. M.; Denis, Simone; Kohlschütter, Alfried; Wanders, Ronald J. A.

    2003-01-01

    Peroxisome biogenesis disorders (PBDs) and D-bifunctional protein (D-BP) deficiency are two types of inherited peroxisomal disorders. Patients with a PBD lack functional peroxisomes and patients with D-BP deficiency lack the enzyme, which is responsible for the second and third step of the

  4. Neurodegeneration in D-bifunctional protein deficiency: diagnostic clues and natural history using serial magnetic resonance imaging

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    Khan, Aneal [University of Calgary, Department of Medical Genetics and Pediatrics, Alberta Children' s Hospital, Calgary, AB (Canada); Wei, Xing-Chang [University of Calgary, Department of Radiology, Alberta Children' s Hospital, Calgary, AB (Canada); Snyder, Floyd F. [Alberta Children' s Hospital, Biochemical Genetics Laboratory, Calgary, AB (Canada); Mah, Jean K. [University of Calgary, Division of Neurology, Department of Pediatrics, Calgary, AB (Canada); Waterham, Hans; Wanders, Ronald J.A. [University of Amsterdam, Academic Medical Center, Lab Genetic Metabolic Diseases, Amsterdam (Netherlands)

    2010-12-15

    We report serial neurodegenerative changes on neuroimaging in a rare peroxisomal disease called D-bifunctional protein deficiency. The pattern of posterior to anterior demyelination with white matter disease resembles X-linked adrenoleukodystrophy. We feel this case is important to (1) highlight that D-bifunctional protein deficiency should be considered in cases where the neuroimaging resembles X-linked adrenoleukodystrophy, (2) to show different stages of progression to help identify this disease using neuroimaging in children, and (3) to show that neuroimaging suggesting a leukodystrophy can warrant peroxisomal beta-oxidation studies in skin fibroblasts even when plasma very long chain fatty acids are normal. (orig.)

  5. Oriented immobilization of proteins on hydroxyapatite surface using bifunctional bisphosphonates as linkers.

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    Yewle, Jivan N; Wei, Yinan; Puleo, David A; Daunert, Sylvia; Bachas, Leonidas G

    2012-06-11

    Oriented immobilization of proteins is an important step in creating protein-based functional materials. In this study, a method was developed to orient proteins on hydroxyapatite (HA) surfaces, a widely used bone implant material, to improve protein bioactivity by employing enhanced green fluorescent protein (EGFP) and β-lactamase as model proteins. These proteins have a serine or threonine at their N-terminus that was oxidized with periodate to obtain a single aldehyde group at the same location, which can be used for the site-specific immobilization of the protein. The HA surface was modified with bifunctional hydrazine bisphosphonates (HBPs) of various length and lipophilicity. The number of functional groups on the HBP-modified HA surface, determined by a 2,4,6-trinitrobenzenesulfonic acid (TNBS) assay, was found to be 2.8 × 10(-5) mol/mg of HA and unaffected by the length of HBPs. The oxidized proteins were immobilized on the HBP-modified HA surface in an oriented manner through formation of a hydrazone bond. The relative protein immobilization amounts through various HBPs were determined by fluorescence and bicinchoninic acid (BCA) assay and showed no significant effect by length and lipophilicity of HBPs. The relative amount of HBP-immobilized EGFP was found to be 10-15 fold that of adsorbed EGFP, whereas the relative amount of β-lactamase immobilized through HBPs (2, 3, 4, 6, and 7) was not significantly different than adsorbed β-lactamase. The enzymatic activity of HBP-immobilized β-lactamase was measured with cefazolin as substrate, and it was found that the catalytic efficiency of HBP-immobilized β-lactamase improved 2-5 fold over adsorbed β-lactamase. The results obtained demonstrate the feasibility of our oriented immobilization approach and showed an increased activity of the oriented proteins in comparison with adsorbed proteins on the same hydroxyapatite surface matrix.

  6. Development of a bifunctional filter for prion protein and leukoreduction of red blood cell components.

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    Yokomizo, Tomo; Kai, Takako; Miura, Morikazu; Ohto, Hitoshi

    2015-02-01

    Leukofiltration of blood components is currently implemented worldwide as a precautionary measure against white blood cell-associated adverse effects and the potential transmission of variant Creutzfeldt-Jakob disease (vCJD). A newly developed bifunctional filter (Sepacell Prima, Asahi Kasei Medical) was assessed for prion removal, leukoreduction (LR), and whether the filter significantly affected red blood cells (RBCs). Sepacell Prima's postfiltration effects on RBCs, including hemolysis, complement activation, and RBC chemistry, were compared with those of a conventional LR filter (Sepacell Pure RC). Prion removal was measured by Western blot after spiking RBCs with microsomal fractions derived from scrapie-infected hamster brain homogenate. Serially diluted exogenous prion solutions (0.05 mL), with or without filtration, were injected intracerebrally into Golden Syrian hamsters. LR efficiency of 4.44 log with the Sepacell Prima was comparable to 4.11 log with the conventional LR filter. There were no significant differences between the two filters in hemoglobin loss, hemolysis, complement activation, and RBC biomarkers. In vitro reduction of exogenously spiked prions by the filter exceeded 3 log. The titer, 6.63 (log ID50 /mL), of prefiltration infectivity of healthy hamsters was reduced to 2.52 (log ID50 /mL) after filtration. The reduction factor was calculated as 4.20 (log ID50 ). With confirmed removal efficacy for exogenous prion protein, this new bifunctional prion and LR filter should reduce the residual risk of vCJD transmission through blood transfusion without adding complexity to component processing. © 2014 AABB.

  7. Bifunctional fatty acid chemical reporter for analyzing S-palmitoylated membrane protein-protein interactions in mammalian cells.

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    Peng, Tao; Hang, Howard C

    2015-01-21

    Studying the functions of S-palmitoylated proteins in cells can be challenging due to the membrane targeting property and dynamic nature of protein S-palmitoylation. New strategies are therefore needed to specifically capture S-palmitoylated protein complexes in cellular membranes for dissecting their functions in vivo. Here we present a bifunctional fatty acid chemical reporter, x-alk-16, which contains an alkyne and a diazirine, for metabolic labeling of S-palmitoylated proteins and photo-cross-linking of their involved protein complexes in mammalian cells. We demonstrate that x-alk-16 can be metabolically incorporated into known S-palmitoylated proteins such as H-Ras and IFITM3, a potent antiviral protein, and induce covalent cross-linking of IFITM3 oligomerization as well as its specific interactions with other membrane proteins upon in-cell photoactivation. Moreover, integration of x-alk-16-induced photo-cross-linking with label-free quantitative proteomics allows identification of new IFITM3 interacting proteins.

  8. Development of a spectroscopic assay for bifunctional ligand-protein conjugates based on copper

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    Brady, Erik D. E-mail: bradye@mail.nih.gov; Chong, Hyun-Soon; Milenic, Diane E.; Brechbiel, Martin W

    2004-08-01

    A simple, non-radioactive method for the determination of ligand-to-protein ratio (L/P) for novel ligand-antibody conjugates has been developed based on an exchange equilibrium with the purple Cu(II) complex of arsenazo III. The method requires a UV/Vis spectrometer and has been verified for monoclonal antibody Herceptin conjugates of a variety of ligand modalities, including common macrocyclic compounds NOTA and TETA, and with a new bifunctional tachpyridine (1H-Pyrrole-1-butanamide,N-[4-[[(1{alpha},3{alpha},5{alpha})-3,5-bis[(2-pyridi= nylmethyl) amino]cyclohexyl](2-pyridinylmethyl)amino]butyl]-2,5-dihydro-2, 5-dioxo-(9CI)). The spectroscopically derived values for L/P were verified by titration of the ligand-antibody conjugate with {sup 64}Cu. In each case, the value obtained by UV/Vis spectroscopy matches that found by radiolabeling. The method is rapid, taking less than 30 minutes with each ligand in this study.

  9. Lactoferrin binding protein B - a bi-functional bacterial receptor protein.

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    Nicholas K H Ostan

    2017-03-01

    Full Text Available Lactoferrin binding protein B (LbpB is a bi-lobed outer membrane-bound lipoprotein that comprises part of the lactoferrin (Lf receptor complex in Neisseria meningitidis and other Gram-negative pathogens. Recent studies have demonstrated that LbpB plays a role in protecting the bacteria from cationic antimicrobial peptides due to large regions rich in anionic residues in the C-terminal lobe. Relative to its homolog, transferrin-binding protein B (TbpB, there currently is little evidence for its role in iron acquisition and relatively little structural and biophysical information on its interaction with Lf. In this study, a combination of crosslinking and deuterium exchange coupled to mass spectrometry, information-driven computational docking, bio-layer interferometry, and site-directed mutagenesis was used to probe LbpB:hLf complexes. The formation of a 1:1 complex of iron-loaded Lf and LbpB involves an interaction between the Lf C-lobe and LbpB N-lobe, comparable to TbpB, consistent with a potential role in iron acquisition. The Lf N-lobe is also capable of binding to negatively charged regions of the LbpB C-lobe and possibly other sites such that a variety of higher order complexes are formed. Our results are consistent with LbpB serving dual roles focused primarily on iron acquisition when exposed to limited levels of iron-loaded Lf on the mucosal surface and effectively binding apo Lf when exposed to high levels at sites of inflammation.

  10. A novel bifunctional protein TNFR2-Fc-IL-1ra (TFI): expression, purification and its neutralization activity of inflammatory factors.

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    Xie, Bo; Liu, Shan; Wu, Shuyin; Chang, Alan; Jin, Weiyuan; Guo, Zhixiang; Ye, Shuaidong; Hui, Mizhou

    2013-06-01

    Tumor necrosis factor receptor (TNF) and internleukin-1 (IL-1) are the most potent proinflammatory cytokines involving in autoimmune and inflammatory human diseases. Many anti-inflammatory agents have been exploited for anti-inflammation treatments by targeting cytokines including TNF and IL-1. Theoretically, simultaneously neutralizing or blocking two important inflammatory mediators may achieve a synergistic therapeutic effect. We have developed a recombinant fusion protein, TNFR2-Fc-IL-1ra (TFI), which consists of a TNF-neutralizing domain that specifically binds to TNF-α, an IL-1 receptor antagonist domain, and a dimerization Fc portion of human IgG1, for bifunctional inflammatory inhibitor. Recombinant DNA expressing the sequence of this fusion protein was expressed in CHO-S cells. The protein product was purified using a two-step purification protocol and the identity of the protein was confirmed by western blot analysis. The purified recombinant protein had a purity of about 98 % as determined by HPLC, and a molecular mass of 164.6 kDa as determined by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. The results of cell binding inhibition indicate that TFI was able to strongly neutralize TNF activity and antagonize IL-1r activity, suggesting that TFI may be used as a bifunctional ligand with enhanced anti-inflammatory effect. The result obtained in this study may provide a platform for extending bifunctional anti-inflammatory drug development.

  11. A novel HPLC-based method to diagnose peroxisomal D-bifunctional protein enoyl-CoA hydratase deficiency.

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    Gloerich, Jolein; Denis, Simone; van Grunsven, Elisabeth G; Dacremont, Georges; Wanders, Ronald J A; Ferdinandusse, Sacha

    2003-03-01

    D-bifunctional protein (D-BP) plays an indispensable role in peroxisomal beta-oxidation, and its inherited deficiency in humans is associated with severe clinical abnormalities. Three different subtypes of D-BP deficiency can be distinguished: 1) a complete deficiency of D-BP (type I), 2) an isolated D-BP enoyl-CoA hydratase deficiency (type II), and 3) an isolated D-BP 3-hydroxyacyl-CoA dehydrogenase deficiency (type III). In this study, we developed a method to measure D-BP dehydrogenase activity independent of D-BP hydratase (D-BP HY) activity to distinguish between D-BP deficiency type I and type II, which until now was only possible by mutation analysis. For this assay, the hydratase domain of D-BP was expressed in the yeast Saccharomyces cerevisiae. After a coincubation of yeast homogenate expressing D-BP HY with fibroblast homogenate of patients using the enoyl-CoA ester of the bile acid intermediate trihydroxycholestanoic acid as substrate, D-BP dehydrogenase activity was measured. Fibroblasts of patients with a D-BP deficiency type II displayed D-BP dehydrogenase activity, whereas type I and type III patients did not. This newly developed assay to measure D-BP dehydrogenase activity in fibroblast homogenates provides a quick and reliable method to assign patients with deficient D-BP HY activity to the D-BP deficiency subgroups type I or type II.

  12. Conversion of β-carotene into astaxanthin: Two separate enzymes or a bifunctional hydroxylase-ketolase protein?

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    Gudiña Eduardo

    2008-02-01

    Full Text Available Abstract Astaxanthin is a xanthophyll of great interest in animal nutrition and human health. The market prospect in the nutraceutics industries for this health-protective molecule is very promising. Astaxanthin is synthesized by several bacteria, algae and plants from β-carotene by the sequential action of two enzymes: a β-carotene, 3,3'-hydroxylase that introduces an hydroxyl group at the 3 (and 3' positions of each of the two β-ionone rings of β-carotene, and a β-carotene ketolase that introduces keto groups at carbons 4 and 4' of the β-ionone rings. Astaxanthin is also produced by the yeast-like basidiomycete Xanthophyllomyces dendrorhous. A gene crtS involved in the conversion of β-carotene to astaxanthin has been cloned simultaneously by two research groups. Complementation studies of X. dendrorhous mutants and expression analysis in Mucor circinelloides reveals that the CrtS enzyme is a β-carotene hydroxylase of the P-450 monooxygenase family that converts β-carotene to the hydroxylated derivatives β-cryptoxanthin and zeaxanthin, but it does not form astaxanthin or the ketolated intermediates in this fungus. A bifunctional β-carotene hydroxylase-ketolase activity has been proposed for the CrtS protein. The evidence for and against this hypothesis is analyzed in detail in this review.

  13. Characterization of Bifunctional Spin Labels for Investigating the Structural and Dynamic Properties of Membrane Proteins Using EPR Spectroscopy.

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    Sahu, Indra D; Craig, Andrew F; Dunagum, Megan M; McCarrick, Robert M; Lorigan, Gary A

    2017-10-05

    Site-directed spin labeling (SDSL) coupled with electron paramagnetic resonance (EPR) spectroscopy is a very powerful technique to study structural and dynamic properties of membrane proteins. The most widely used spin label is methanthiosulfonate (MTSL). However, the flexibility of this spin label introduces greater uncertainties in EPR measurements obtained for determining structures, side-chain dynamics, and backbone motion of membrane protein systems. Recently, a newer bifunctional spin label (BSL), 3,4-bis(methanethiosulfonylmethyl)-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yloxy, has been introduced to overcome the dynamic limitations associated with the MTSL spin label and has been invaluable in determining protein backbone dynamics and inter-residue distances due to its restricted internal motion and fewer size restrictions. While BSL has been successful in providing more accurate information about the structure and dynamics of several proteins, a detailed characterization of the spin label is still lacking. In this study, we characterized BSLs by performing CW-EPR spectral line shape analysis as a function of temperature on spin-labeled sites inside and outside of the membrane for the integral membrane protein KCNE1 in POPC/POPG lipid bilayers and POPC/POPG lipodisq nanoparticles. The experimental data revealed a powder pattern spectral line shape for all of the KCNE1-BSL samples at 296 K, suggesting the motion of BSLs approaches the rigid limit regime for these series of samples. BSLs were further utilized to report for the first time the distance measurement between two BSLs attached on an integral membrane protein KCNE1 in POPC/POPG lipid bilayers at room temperature using dipolar line broadening CW-EPR spectroscopy. The CW dipolar line broadening EPR data revealed a 15 ± 2 Å distance between doubly attached BSLs on KCNE1 (53/57-63/67) which is consistent with molecular dynamics modeling and the solution NMR structure of KCNE1 which yielded a

  14. The Cytophaga hutchinsonii ChTPSP: First characterized bifunctional TPS-TPP protein as putative ancestor of all eukaryotic trehalose biosynthesis proteins.

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    Avonce, Nelson; Wuyts, Jan; Verschooten, Katrien; Vandesteene, Lies; Van Dijck, Patrick

    2010-02-01

    The most widely distributed pathway to synthesize trehalose in nature consists of two consecutive enzymatic reactions with a trehalose-6-P (T6P)-synthase (TPS) enzyme, producing the intermediate T6P, and a T6P-phosphatase (TPP) enzyme, which dephosphorylates T6P to produce trehalose and inorganic phosphate. In plants, these enzymes are called Class I and Class II proteins, respectively, with some Class I proteins being active enzymes. The Class II proteins possess both TPS and TPP consensus regions but appear to have lost enzymatic activity during evolution. Plants also contain an extra group of enzymes of small protein size, of which some members have been characterized as functional TPPs. These Class III proteins have less sequence similarity with the Class I and Class II proteins. Here, we characterize for the first time, by using biochemical analysis and yeast growth complementation assays, the existence of a natural TPS-TPP bifunctional enzyme found in the bacterial species Cytophaga hutchinsonii. Through phylogenetic analysis, we show that prokaryotic genes such as ChTPSP might be the ancestor of the eukaryotic trehalose biosynthesis genes. Second, we show that plants have recruited during evolution, possibly by horizontal transfer from bacteria such as Rhodoferax ferrireducens, a new type of small protein, encoding TPP activity, which have been named Class III proteins. RfTPP has very high TPP activity upon expression in yeast. Finally, we demonstrate that TPS gene duplication, the recruitment of the Class III enzymes, and recruitment of an N-terminal regulatory element, which regulates the Class I enzyme activity in higher plants, were initiated very early in eukaryan evolution as the three classes of trehalose biosynthesis genes are already present in the alga Ostreococcus tauri.

  15. Construction of bifunctional molecules specific to antigen and antibody’s Fc-fragment by fusion of scFv-antibodies with staphylococcal protein A

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    Kolibo D. V.

    2009-06-01

    Full Text Available Aim. To develop approach for detection of scFv and their complexes with antigens. Methods. The fusion proteins, which include sequences of scFv and staphylococcal protein A, were constructed and the obtained bifunctional molecules were immunochemically analysed. Results. It was shown, that scFv fused with protein A and their complexes with antigens are effectively recognized by labelled immunoglobulins with unrestricted antigenic specificity. Conclusions. The fusion of scFv with protein A fragment is a perspective approach to increase the efficiency of application in ELISA. The obtained scFv, fused with protein A, could be used for development of test-systems for the detection of diphtheria toxin.

  16. Bifunctional recombinant fusion proteins for rapid detection of antibodies to both HIV-1 and HIV-2 in whole blood

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    Chaudhary Vijay K

    2006-09-01

    Full Text Available Abstract Background Availability of accurate diagnostic tests has been helpful in curtailing the spread of HIV infection. Among these, simple, point of care, inexpensive tests which require only a drop of blood from finger-prick and give reliable results within minutes are a must for expansion of testing services and for reaching mobile and marginalised populations. Such tests will not only be a boon for the infrastructure-starved developing and underdeveloped countries but will also be extremely useful in developed countries where post-testing compliance is a major problem. Our laboratory has been involved in developing reagents for heamagglutination-based rapid detection of antibodies to HIV in whole blood using recombinant molecules specific for either HIV-1 or HIV-2. Since it is not required of a screening test to differentially detect HIV and HIV-2, it would useful to create a single molecule capable of simultaneous detection of both HIV-1 and HIV-2 in a drop of blood. Results The present paper describes designing, high-level expression and large-scale purification of new molecules comprising recombinant anti-RBC Fab fused to immunodominant regions of envelope sequences from both gp41 of HIV-1 and gp36 of HIV-2. These immunodominant regions of HIV envelope contain cysteine residues, which make disulfide bond and can interfere with the assembly of light chain and heavy chain fragment to make Fab molecule in vitro. To circumvent this problem, a series of fusion proteins having different combinations of native and mutant envelope sequences were constructed, purified and evaluated for their efficacy in detecting antibodies to HIV-1 and HIV-2. A chimeric molecule comprising native envelope sequence of gp41 of HIV-1 and modified envelope sequence of gp36 of HIV-2 gave good production yield and also detected both HIV-1 and HIV-2 samples with high sensitivity and specificity. Conclusion The new bifunctional antibody fusion protein identified in

  17. In situ labeling and imaging of cellular protein via a bi-functional anticancer aptamer and its fluorescent ligand.

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    Ai, Jun; Li, Tao; Li, Bingling; Xu, Yuanhong; Li, Dan; Liu, Zuojia; Wang, Erkang

    2012-09-05

    In this article, we reported a novel approach for in situ labeling and imaging HeLa cancer cells utilizing a bifunctional aptamer (AS1411) and its fluorescent ligand, protoporphyrin IX (PPIX). In the presence of potassium ion, AS1411 folded to G-quadruplex structure, binded fluorescent ligand (PPIX) with fluorescent enhancement, and targeted the nucleolin overexpressed by cancer cells. Consequently, bioimaging of cancer cells specifically were realized by laser scanning confocal microscope. The bioimaging strategy with AS1411-PPIX complex was capable to distinguish HeLa cancer cells from normal cells unambiguously, and fluorescence imaging of cancer cells was also realized in human serum. Moreover, the bioimaging method was very facile, effective and need not any covalent modification. These results illustrated that the useful approach can provide a novel clue for bioimaging based on non-covalent bifunctional aptamer in clinic diagnosis. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Effects of naturally occurring missense mutations and G525V in the hydratase domain of human d-bifunctional protein on hydratase activity

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    Shirou Tsuchida

    2015-03-01

    Full Text Available d-bifunctional protein (d-BP deficiency is thought to lead to severe lipid metabolism disorders. To investigate the effect of naturally occurring missense mutations in the hydratase domain in d-BP, we constructed several d-BP hydratase variants and measured their activities. Missense mutations at sites whose conservation rates among 30 eukaryotes were < 70% did not affect hydratase activity. We predicted that missense mutations of highly conserved amino acids would markedly reduce activity. However, R562H and R562L, naturally occurring missense mutations of highly conserved amino acids, did not reduce activity. This result suggests that a missense mutation in a highly conserved amino acid does not always lead to severe lipid metabolism disorders. We also investigated the effect of G525V, which had been found in a mildly symptomatic patient with d-BP deficiency who was heterozygous for G525 and G658X. G525V markedly reduced hydratase activity. We had predicted that heterozygous G525V and G658X would lead to severely disordered lipid metabolism. However, the symptoms were inconsistent with this prediction. Characterizing mutations in the d-BP gene and the symptoms of d-BP deficiency may require pleiotropy, not only in vitro, studies.

  19. Bifunctional anti-huntingtin proteasome-directed intrabodies mediate efficient degradation of mutant huntingtin exon 1 protein fragments.

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    David C Butler

    Full Text Available Huntington's disease (HD is a fatal autosomal dominant neurodegenerative disorder caused by a trinucleotide (CAG(n repeat expansion in the coding sequence of the huntingtin gene, and an expanded polyglutamine (>37Q tract in the protein. This results in misfolding and accumulation of huntingtin protein (htt, formation of neuronal intranuclear and cytoplasmic inclusions, and neuronal dysfunction/degeneration. Single-chain Fv antibodies (scFvs, expressed as intrabodies that bind htt and prevent aggregation, show promise as immunotherapeutics for HD. Intrastriatal delivery of anti-N-terminal htt scFv-C4 using an adeno-associated virus vector (AAV2/1 significantly reduces the size and number of aggregates in HDR6/1 transgenic mice; however, this protective effect diminishes with age and time after injection. We therefore explored enhancing intrabody efficacy via fusions to heterologous functional domains. Proteins containing a PEST motif are often targeted for proteasomal degradation and generally have a short half life. In ST14A cells, fusion of the C-terminal PEST region of mouse ornithine decarboxylase (mODC to scFv-C4 reduces htt exon 1 protein fragments with 72 glutamine repeats (httex1-72Q by ~80-90% when compared to scFv-C4 alone. Proteasomal targeting was verified by either scrambling the mODC-PEST motif, or via proteasomal inhibition with epoxomicin. For these constructs, the proteasomal degradation of the scFv intrabody proteins themselves was reduced<25% by the addition of the mODC-PEST motif, with or without antigens. The remaining intrabody levels were amply sufficient to target N-terminal httex1-72Q protein fragment turnover. Critically, scFv-C4-PEST prevents aggregation and toxicity of httex1-72Q fragments at significantly lower doses than scFv-C4. Fusion of the mODC-PEST motif to intrabodies is a valuable general approach to specifically target toxic antigens to the proteasome for degradation.

  20. Specific combination of compound heterozygous mutations in 17β-hydroxysteroid dehydrogenase type 4 (HSD17B4 defines a new subtype of D-bifunctional protein deficiency

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    McMillan Hugh J

    2012-11-01

    Full Text Available Abstract Background D-bifunctional protein (DBP deficiency is typically apparent within the first month of life with most infants demonstrating hypotonia, psychomotor delay and seizures. Few children survive beyond two years of age. Among patients with prolonged survival all demonstrate severe gross motor delay, absent language development, and severe hearing and visual impairment. DBP contains three catalytically active domains; an N-terminal dehydrogenase, a central hydratase and a C-terminal sterol carrier protein-2-like domain. Three subtypes of the disease are identified based upon the domain affected; DBP type I results from a combined deficiency of dehydrogenase and hydratase activity; DBP type II from isolated hydratase deficiency and DBP type III from isolated dehydrogenase deficiency. Here we report two brothers (16½ and 14 years old with DBP deficiency characterized by normal early childhood followed by sensorineural hearing loss, progressive cerebellar and sensory ataxia and subclinical retinitis pigmentosa. Methods and results Biochemical analysis revealed normal levels of plasma VLCFA, phytanic acid and pristanic acid, and normal bile acids in urine; based on these results no diagnosis was made. Exome analysis was performed using the Agilent SureSelect 50Mb All Exon Kit and the Illumina HiSeq 2000 next-generation-sequencing (NGS platform. Compound heterozygous mutations were identified by exome sequencing and confirmed by Sanger sequencing within the dehydrogenase domain (c.101C>T; p.Ala34Val and hydratase domain (c.1547T>C; p.Ile516Thr of the 17β-hydroxysteroid dehydrogenase type 4 gene (HSD17B4. These mutations have been previously reported in patients with severe-forms of DBP deficiency, however each mutation was reported in combination with another mutation affecting the same domain. Subsequent studies in fibroblasts revealed normal VLCFA levels, normal C26:0 but reduced pristanic acid beta-oxidation activity. Both DBP

  1. Identification of Antithrombin-Modulating Genes. Role of LARGE, a Gene Encoding a Bifunctional Glycosyltransferase, in the Secretion of Proteins?

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    de la Morena-Barrio, María Eugenia; Buil, Alfonso; Antón, Ana Isabel; Martínez-Martínez, Irene; Miñano, Antonia; Gutiérrez-Gallego, Ricardo; Navarro-Fernández, José; Aguila, Sonia; Souto, Juan Carlos; Vicente, Vicente; Soria, José Manuel; Corral, Javier

    2013-01-01

    The haemostatic relevance of antithrombin together with the low genetic variability of SERPINC1, and the high heritability of plasma levels encourage the search for modulating genes. We used a hypothesis-free approach to identify these genes, evaluating associations between plasma antithrombin and 307,984 polymorphisms in the GAIT study (352 individuals from 21 Spanish families). Despite no SNP reaching the genome wide significance threshold, we verified milder positive associations in 307 blood donors from a different cohort. This validation study suggested LARGE, a gene encoding a protein with xylosyltransferase and glucuronyltransferase activities that forms heparin-like linear polysaccharides, as a potential modulator of antithrombin based on the significant association of one SNPs, rs762057, with anti-FXa activity, particularly after adjustment for age, sex and SERPINC1 rs2227589 genotype, all factors influencing antithrombin levels (p = 0.02). Additional results sustained this association. LARGE silencing inHepG2 and HEK-EBNA cells did not affect SERPINC1 mRNA levels but significantly reduced the secretion of antithrombin with moderate intracellular retention. Milder effects were observed on α1-antitrypsin, prothrombin and transferrin. Our study suggests LARGE as the first known modifier of plasma antithrombin, and proposes a new role for LARGE in modulating extracellular secretion of certain glycoproteins. PMID:23705025

  2. Inactivation of caspase-8 on mitochondria of Bcl-xL-expressing MCF7-Fas cells: role for the bifunctional apoptosis regulator protein.

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    Stegh, Alexander H; Barnhart, Bryan C; Volkland, Jorg; Algeciras-Schimnich, Alicia; Ke, Ning; Reed, John C; Peter, Marcus E

    2002-02-08

    Apoptosis induction through CD95 (APO-1/Fas) critically depends on generation of active caspase-8 at the death-inducing signaling complex (DISC). Depending on the cell type, active caspase-8 either directly activates caspase-3 (type I cells) or relies on mitochondrial signal amplification (type II cells). In MCF7-Fas cells that are deficient for pro-caspase-3, even high amounts of caspase-8 produced at the DISC cannot directly activate downstream effector caspases without mitochondrial help. Overexpression of Bcl-x(L) in these cells renders them resistant to CD95-mediated apoptosis. However, activation of caspase-8 in control (vector) and Bcl-x(L) transfectants of MCF7-Fas cells proceeds with similar kinetics, resulting in a complete processing of cellular caspase-8. Most of the cytosolic caspase-8 substrates are not cleaved in the Bcl-x(L) protected cells, raising the question of how Bcl-x(L)-expressing MCF7-Fas cells survive large amounts of potentially cytotoxic caspase-8. We now demonstrate that active caspase-8 is initially generated at the DISC of both MCF7-Fas-Vec and MCF7-Fas-Bcl-x(L) cells and that the early steps of CD95 signaling such as caspase-8-dependent cleavage of DISC bound c-FLIP(L), caspase-8-dependent clustering, and internalization of CD95, as well as processing of pro-caspase-8 bound to mitochondria are very similar in both transfectants. However, events downstream of mitochondria, such as release of cytochrome c, only occur in the vector-transfected MCF7-Fas cells, and no in vivo caspase-8 activity can be detected in the Bcl-x(L)-expressing cells. Our data suggest that, in Bcl-x(L)-expressing MCF7-Fas cells, active caspase-8 is sequestered on the outer mitochondrial surface presumably by association with the protein "bifunctional apoptosis regulator" in a way that does not allow substrates to be cleaved, identifying a novel mechanism of regulation of apoptosis sensitivity by mitochondrial Bcl-x(L).

  3. Chrysanthemyl diphosphate synthase operates in planta as a bifunctional enzyme with chrysanthemol synthase activity

    DEFF Research Database (Denmark)

    Yang, Ting; Gao, Liping; Hu, Hao

    2014-01-01

    (CPP). Three proteins are known to catalyze this cyclopropanation reaction of terpene precursors. Two of them, phytoene and squalene synthase, are bifunctional enzymes with both prenyltransferase and terpene synthase activity. CDS, the other member, has been reported to perform only...

  4. Cytotoxic effect of co-expression of human hepatitis A virus 3C protease and bifunctional suicide protein FCU1 genes in a bicistronic vector.

    Science.gov (United States)

    Komissarov, Alexey; Demidyuk, Ilya; Safina, Dina; Roschina, Marina; Shubin, Andrey; Lunina, Nataliya; Karaseva, Maria; Kostrov, Sergey

    2017-08-01

    Recent reports on various cancer models demonstrate a great potential of cytosine deaminase/5-fluorocytosine suicide system in cancer therapy. However, this approach has limited success and its application to patients has not reached the desirable clinical significance. Accordingly, the improvement of this suicide system is an actively developing trend in gene therapy. The purpose of this study was to explore the cytotoxic effect observed after co-expression of hepatitis A virus 3C protease (3C) and yeast cytosine deaminase/uracil phosphoribosyltransferase fusion protein (FCU1) in a bicistronic vector. A set of mono- and bicistronic plasmid constructs was generated to provide individual or combined expression of 3C and FCU1. The constructs were introduced into HEK293 and HeLa cells, and target protein synthesis as well as the effect of 5-fluorocytosine on cell death and the time course of the cytotoxic effect was studied. The obtained vectors provide for the synthesis of target proteins in human cells. The expression of the genes in a bicistronic construct provide for the cytotoxic effect comparable to that observed after the expression of genes in monocistronic constructs. At the same time, co-expression of FCU1 and 3C recapitulated their cytotoxic effects. The combined effect of the killer and suicide genes was studied for the first time on human cells in vitro. The integration of different gene therapy systems inducing cell death (FCU1 and 3C genes) in a bicistronic construct allowed us to demonstrate that it does not interfere with the cytotoxic effect of each of them. A combination of cytotoxic genes in multicistronic vectors can be used to develop pluripotent gene therapy agents.

  5. Tailored bifunctional polymer for plutonium monitoring.

    Science.gov (United States)

    Paul, Sumana; Pandey, Ashok K; Kumar, Pranaw; Kaity, Santu; Aggarwal, Suresh K

    2014-07-01

    Monitoring of actinides with sophisticated conventional methods is affected by matrix interferences, spectral interferences, isobaric interferences, polyatomic interferences, and abundance sensitivity problems. To circumvent these limitations, a self-supported disk and membrane-supported bifunctional polymer were tailored in the present work for acidity-dependent selectivity toward Pu(IV). The bifunctional polymer was found to be better than the polymer containing either a phosphate group or a sulfonic acid group in terms of (i) higher Pu(IV) sorption efficiency at 3-4 mol L(-1) HNO3, (ii) selective preconcentration of Pu(IV) in the presence of a trivalent actinide such as Am(III), and (iii) preferential sorption of Pu(IV) in the presence of a large excess of U(VI). The bifunctional polymer was formed as a self-supported matrix by bulk polymerization and also as a 1-2 μm thin layer anchored on a microporous poly(ether sulfone) by surface grafting. The proportions of sulfonic acid and phosphate groups in both the self-supported disk and membrane-supported bifunctional polymer were found to be the same as expected from the mole proportions of monomers in polymerizing solutions used for syntheses. α radiography by a solid-state nuclear track detector indicated fairly homogeneous anchoring of the bifunctional polymer on the surface of the membrane. Pu(IV) preconcentrated on a single bifunctional bead was used for determination of the Pu isotopic composition by thermal ionization mass spectrometry. The membrane-supported bifunctional polymer was used for preconcentration and subsequent quantification of Pu(IV) by α spectrometry using the absolute efficiency at a fixed counting geometry. The analytical performance of the membrane-supported-bifunctional-polymer-based α spectrometry method was found to be highly reproducible for assay of Pu(IV) in a variety of complex samples.

  6. Novel bifunctional molecule for photorefractive materials

    NARCIS (Netherlands)

    Bolink, H.J; Arts, C.; Krasnikov, V.V.; Malliaras, G.G; Hadziioannou, G

    We report on the synthesis and characterization of a novel photorefractive polymer composite that consists of a bifunctional molecule based on the charge-transport molecule N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine (TPD). It is shown that the low values obtained for the

  7. Synthesis and evaluation of novel bifunctional chelating agents based on 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid for radiolabeling proteins

    Energy Technology Data Exchange (ETDEWEB)

    Chappell, L.L.; Ma, D.; Milenic, D.E.; Garmestani, K.; Venditto, V.; Beitzel, M.P.; Brechbiel, M.W. E-mail: martinwb@mail.nih.gov

    2003-08-01

    Detailed synthesis of the bifunctional chelating agents 2-methyl-6-(p-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10 -tetraacetic acid (1B4M-DOTA) and 2-(p-isothiocyanatobenzyl)-5, 6-cyclohexano-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetate (CHX-DOTA) are reported. These chelating agents were compared to 2-(p-isothiocyanatobenzyl)-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (C-DOTA) and 1, 4, 7, 10-Tetraaza-N-(1-carboxy-3-(4-nitrophenyl)propyl)-N', N'', N'''-tris(acetic acid) cyclododecane (PA-DOTA) as their {sup 177}Lu radiolabeled conjugates with Herceptin{sup TM}. In vitro stability of the immunoconjugates radiolabeled with {sup 177}Lu was assessed by serum stability studies. The in vivo stability of the radiolabeled immunoconjugates and their targeting characteristics were determined by biodistribution studies in LS-174T xenograft tumor-bearing mice. Relative radiolabeling rates and efficiencies were determined for all four immunoconjugates. Insertion of the 1B4M moiety into the DOTA backbone increases radiometal chelation rate and provides complex stability comparable to C-DOTA and PA-DOTA while the CHX-DOTA appears to not form as stable a {sup 177}Lu complex while exhibiting a substantial increase in formation rate. The 1B4M-DOTAmay have potential for radioimmunotherapy applications. Published by Elsevier Inc. All rights reserved.

  8. Targeting Prostate Cancer with Bifunctional Modulators of the Androgen Receptor

    Science.gov (United States)

    2013-10-01

    and ProduXion Manager® from Aries Systems Corporation 2 Bifunctional Ligand Control of Nuclear Receptors 1 Bifunctional Ligands Allow...androgen receptor. Genes Dev 21:2005-2017 23. Inohara N, Koseki T, Lin J, del Peso L, Lucas PC, Chen FF, Ogura Y, Núñez G 2000 An Induced Proximity

  9. Bifunctional Elastin-like Polypeptide Nanoparticles Bind Rapamycin and Integrins and Suppress Tumor Growth in Vivo.

    Science.gov (United States)

    Dhandhukia, Jugal P; Shi, Pu; Peddi, Santosh; Li, Zhe; Aluri, Suhaas; Ju, Yaping; Brill, Dab; Wang, Wan; Janib, Siti M; Lin, Yi-An; Liu, Shuanglong; Cui, Honggang; MacKay, J Andrew

    2017-11-15

    Recombinant protein-polymer scaffolds such as elastin-like polypeptides (ELPs) offer drug-delivery opportunities including biocompatibility, monodispersity, and multifunctionality. We recently reported that the fusion of FK-506 binding protein 12 (FKBP) to an ELP nanoparticle (FSI) increases rapamycin (Rapa) solubility, suppresses tumor growth in breast cancer xenografts, and reduces side effects observed with free-drug controls. This new report significantly advances this carrier strategy by demonstrating the coassembly of two different ELP diblock copolymers containing drug-loading and tumor-targeting domains. A new ELP nanoparticle (ISR) was synthesized that includes the canonical integrin-targeting ligand (Arg-Gly-Asp, RGD). FSI and ISR mixed in a 1:1 molar ratio coassemble into bifunctional nanoparticles containing both the FKBP domain for Rapa loading and the RGD ligand for integrin binding. Coassembled nanoparticles were evaluated for bifunctionality by performing in vitro cell-binding and drug-retention assays and in vivo MDA-MB-468 breast tumor regression and tumor-accumulation studies. The bifunctional nanoparticle demonstrated superior cell target binding and similar drug retention to FSI; however, it enhanced the formulation potency, such that tumor growth was suppressed at a 3-fold lower dose compared to an untargeted FSI-Rapa control. This data suggests that ELP-mediated scaffolds are useful tools for generating multifunctional nanomedicines with potential activity in cancer.

  10. Reciprocal Regulation as a Source of Ultrasensitivity in Two-Component Systems with a Bifunctional Sensor Kinase

    Science.gov (United States)

    Straube, Ronny

    2014-01-01

    Two-component signal transduction systems, where the phosphorylation state of a regulator protein is modulated by a sensor kinase, are common in bacteria and other microbes. In many of these systems, the sensor kinase is bifunctional catalyzing both, the phosphorylation and the dephosphorylation of the regulator protein in response to input signals. Previous studies have shown that systems with a bifunctional enzyme can adjust the phosphorylation level of the regulator protein independently of the total protein concentrations – a property known as concentration robustness. Here, I argue that two-component systems with a bifunctional enzyme may also exhibit ultrasensitivity if the input signal reciprocally affects multiple activities of the sensor kinase. To this end, I consider the case where an allosteric effector inhibits autophosphorylation and, concomitantly, activates the enzyme's phosphatase activity, as observed experimentally in the PhoQ/PhoP and NRII/NRI systems. A theoretical analysis reveals two operating regimes under steady state conditions depending on the effector affinity: If the affinity is low the system produces a graded response with respect to input signals and exhibits stimulus-dependent concentration robustness – consistent with previous experiments. In contrast, a high-affinity effector may generate ultrasensitivity by a similar mechanism as phosphorylation-dephosphorylation cycles with distinct converter enzymes. The occurrence of ultrasensitivity requires saturation of the sensor kinase's phosphatase activity, but is restricted to low effector concentrations, which suggests that this mode of operation might be employed for the detection and amplification of low abundant input signals. Interestingly, the same mechanism also applies to covalent modification cycles with a bifunctional converter enzyme, which suggests that reciprocal regulation, as a mechanism to generate ultrasensitivity, is not restricted to two-component systems, but

  11. Astaxanthin diferulate as a bifunctional antioxidant

    DEFF Research Database (Denmark)

    Papa, T.B.R.; Pinho, V.D.; Nascimento, E.P. do

    2015-01-01

    Abstract Astaxanthin when esterified with ferulic acid is better singlet oxygen quencher with k2 = (1.58 ± 0.1) 10(10) L mol(- 1)s(- 1) in ethanol at 25°C compared with astaxanthin with k2 = (1.12 ± 0.01) 10(9) L mol(- 1)s(- 1). The ferulate moiety in the astaxanthin diester is a better radical s....... The mutual enhancement of antioxidant activity for the newly synthetized astaxanthin diferulate becoming a bifunctional antioxidant is rationalized according to a two-dimensional classification plot for electron donation and electron acceptance capability....

  12. Single Flexible Nanofiber to Simultaneously Realize Electricity-Magnetism Bifunctionality

    OpenAIRE

    Yang, Ming; Sheng,Shujuan; Ma, Qianli; Lv, Nan; Yu, Wensheng; Wang, Jinxian; Dong,Xiangting; Liu, Guixia

    2016-01-01

    In order to develop new-typed multifunctional composite nanofibers, PANI/Fe3O4/PVP flexible bifunctional composite nanofibers with simultaneous electrical conduction and magnetism have been successfully fabricated via a facile electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of polyaniline (PANI) and Fe3O4 nanoparticles (NPs). The bifunctional composite nanofibers simultaneously possess excellent electri...

  13. Bifunctional avidin with covalently modifiable ligand binding site.

    Directory of Open Access Journals (Sweden)

    Jenni Leppiniemi

    Full Text Available The extensive use of avidin and streptavidin in life sciences originates from the extraordinary tight biotin-binding affinity of these tetrameric proteins. Numerous studies have been performed to modify the biotin-binding affinity of (streptavidin to improve the existing applications. Even so, (streptavidin greatly favours its natural ligand, biotin. Here we engineered the biotin-binding pocket of avidin with a single point mutation S16C and thus introduced a chemically active thiol group, which could be covalently coupled with thiol-reactive molecules. This approach was applied to the previously reported bivalent dual chain avidin by modifying one binding site while preserving the other one intact. Maleimide was then coupled to the modified binding site resulting in a decrease in biotin affinity. Furthermore, we showed that this thiol could be covalently coupled to other maleimide derivatives, for instance fluorescent labels, allowing intratetrameric FRET. The bifunctional avidins described here provide improved and novel tools for applications such as the biofunctionalization of surfaces.

  14. Proteolytic and partial sequencing studies of the bifunctional dihydrofolate reductase-thymidylate synthase from Daucus carota.

    Science.gov (United States)

    Cella, R; Carbonera, D; Orsi, R; Ferri, G; Iadarola, P

    1991-06-01

    The bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) of Daucus carota has been further characterized as regards molecular weight, amino acid composition, protease digestion and microsequencing of proteolytic peptides. Data reported in this paper demonstrate that the carrot protein has a calculated Mr of 124,000 thus indicating that, contrarily to what has previously been suggested, it occurs as a dimer of identical subunits. Results of partial amino acid microsequencing show the presence of sequences highly homologous with those of the active sites of both DHFR and TS from other organisms confirming, at the structural level, the bifunctional nature of the carrot protein. As in the case of Leishmania tropica DHFR-TS, incubation of the carrot protein with V8 protease led to a rapid loss of TS activity while retaining that of DHFR. However the pattern of proteolysis did not allow to establish whether the sequence of domains is DHFR-TS as in Leishmania, or vice versa. Low homology of other amino acid sequences, as judged by computer analysis, and absence of common epitopes indicate an apparent divergence between carrot and leishmanian proteins.

  15. Bifunctional Phosphorus Dendrimers and Their Properties.

    Science.gov (United States)

    Caminade, Anne-Marie; Majoral, Jean-Pierre

    2016-04-23

    Dendrimers are hyperbranched and monodisperse macromolecules, generally considered as a special class of polymers, but synthesized step-by-step. Most dendrimers have a uniform structure, with a single type of terminal function. However, it is often desirable to have at least two different functional groups. This review will discuss the case of bifunctional phosphorus-containing dendrimers, and the consequences for their properties. Besides the terminal functions, dendritic structures may have also a function at the core, or linked off-center to the core, or at the core of dendrons (dendritic wedges). Association of two dendrons having different terminal functions leads to Janus dendrimers (two faces). The internal structure can also possess functional groups on one layer, or linked to one layer, or on several layers. Finally, there are several ways to have two types of terminal functions, besides the case of Janus dendrimers: either each terminal function bears two functions sequentially, or two different functions are linked to each terminal branching point. Examples of each type of structure will be given in this review, as well as practical uses of such sophisticated structures in the fields of fluorescence, catalysis, nanomaterials and biology.

  16. A bifunctional endoglucanase/endoxylanase from Cellulomonas flavigena with potential use in industrial processes at different pH.

    Science.gov (United States)

    Pérez-Avalos, Odilia; Sánchez-Herrera, Leticia M; Salgado, Luis M; Ponce-Noyola, Teresa

    2008-07-01

    Cellulomonas flavigena CDBB-531 was found to secrete a bifunctional cellulase/xylanase with a molecular mass of 49 kDa and pI 4.3. This enzyme was active on Remazol brilliant blue-carboxymethylcellulose (RBB-CMC) and Remazol brilliant blue-xylan (RBB-X). Based on thin-layer chromatographic analysis of the degradation products, the cellulase activity produced glucose, cellobiose, cellotriose, and cellotetraose from CMC as the substrate. When xylan from birchwood was used, end products were xylose, arabinose, and xylobiose. The bifunctional enzyme showed a pH optimum of 6 for cellulase activity and 9 for xylanase activity, which pointed out that this enzyme had separate sites for each activity. In both cases, the apparent optimum temperature was 50 degrees C. The predicted amino acid sequence of purified protein showed similarity with the catalytic domain of several glycosyl hydrolases of family 10.

  17. Robust Control of PEP Formation Rate in the Carbon Fixation Pathway of C4 Plants by a Bi-functional Enzyme

    Directory of Open Access Journals (Sweden)

    Hart Yuval

    2011-10-01

    Full Text Available Abstract Background C4 plants such as corn and sugarcane assimilate atmospheric CO2 into biomass by means of the C4 carbon fixation pathway. We asked how PEP formation rate, a key step in the carbon fixation pathway, might work at a precise rate, regulated by light, despite fluctuations in substrate and enzyme levels constituting and regulating this process. Results We present a putative mechanism for robustness in C4 carbon fixation, involving a key enzyme in the pathway, pyruvate orthophosphate dikinase (PPDK, which is regulated by a bifunctional enzyme, Regulatory Protein (RP. The robust mechanism is based on avidity of the bifunctional enzyme RP to its multimeric substrate PPDK, and on a product-inhibition feedback loop that couples the system output to the activity of the bifunctional regulator. The model provides an explanation for several unusual biochemical characteristics of the system and predicts that the system's output, phosphoenolpyruvate (PEP formation rate, is insensitive to fluctuations in enzyme levels (PPDK and RP, substrate levels (ATP and pyruvate and the catalytic rate of PPDK, while remaining sensitive to the system's input (light levels. Conclusions The presented PPDK mechanism is a new way to achieve robustness using product inhibition as a feedback loop on a bifunctional regulatory enzyme. This mechanism exhibits robustness to protein and metabolite levels as well as to catalytic rate changes. At the same time, the output of the system remains tuned to input levels.

  18. Environmentally Benign Bifunctional Solid Acid and Base Catalysts

    NARCIS (Netherlands)

    Elmekawy, A.; Shiju, N.R.; Rothenberg, G.; Brown, D.R.

    2014-01-01

    Solid bifunctional acid-​base catalysts were prepd. in two ways on an amorphous silica support: (1) by grafting mercaptopropyl units (followed by oxidn. to propylsulfonic acid) and aminopropyl groups to the silica surface (NH2-​SiO2-​SO3H)​, and (2) by grafting only aminopropyl groups and then

  19. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    NARCIS (Netherlands)

    Zecevic, Jovana|info:eu-repo/dai/nl/341386715; Vanbutsele, Gina; de Jong, Krijn P.|info:eu-repo/dai/nl/06885580X; Martens, Johan A.

    2015-01-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts(1-4). Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon

  20. Single flexible nanofiber to simultaneously realize electricity-magnetism bifunctionality

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ming; Sheng, Shujuan; Ma, Qianli; Lv, Nan; Yu, Wensheng; Wang, Jinxian; Dong, Xiangting; Liu, Guixia, E-mail: wenshengyu2009@sina.com, E-mail: dongxiangting888@163.com [Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province, Changchun University of Science and Technology, Changchun (China)

    2016-03-15

    In order to develop new-typed multifunctional composite nanofibers, PANI/Fe{sub 3}O{sub 4}/PVP flexible bifunctional composite nanofibers with simultaneous electrical conduction and magnetism have been successfully fabricated via a facile electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of polyaniline (PANI) and Fe{sub 3}O{sub 4} nanoparticles (NPs). The bifunctional composite nanofibers simultaneously possess excellent electrical conductivity and magnetic properties. The electrical conductivity reaches up to the order of 10{sup -3} S·cm{sup -1}. The electrical conductivity and saturation magnetization of the composite nanofibers can be respectively tuned by adding various amounts of PANI and Fe{sub 3}O{sub 4} NPs. The obtained electricity-magnetism bifunctional composite nanofibers are expected to possess many potential applications in areas such as electromagnetic interference shielding, special coating, microwave absorption, molecular electronics and future nanomechanics. More importantly, the design concept and construct technique are of universal significance to fabricate other bifunctional one-dimensional nanostructures. (author)

  1. Stable expression of a bifunctional diterpene synthase in the chloroplast of Chlamydomonas reinhardtii

    DEFF Research Database (Denmark)

    Zedler, Julie Annemarie Zita; Gangl, Doris; Hamberger, Björn Robert

    2015-01-01

    is an alternative strategy, and we report here the stable expression of a large (91 kDa) protein in the chloroplast using a recently developed low-cost transformation protocol. Moreover, selection of transformants is based on restoration of prototrophy using an endogenous gene (psbH) as the marker, thereby allowing...... the generation of transgenic lines without the use of antibiotic-resistance genes. Here, we have expressed a bifunctional diterpene synthase in C. reinhardtii chloroplasts. Homoplasmic transformants were obtained with the expressed enzyme accounting for 3.7 % of total soluble protein. The enzyme was purified...

  2. AmpH, a bifunctional DD-endopeptidase and DD-carboxypeptidase of Escherichia coli.

    Science.gov (United States)

    González-Leiza, Silvia M; de Pedro, Miguel A; Ayala, Juan A

    2011-12-01

    In Escherichia coli, low-molecular-mass penicillin-binding proteins (LMM PBPs) are important for correct cell morphogenesis. These enzymes display DD-carboxypeptidase and/or dd-endopeptidase activities associated with maturation and remodeling of peptidoglycan (PG). AmpH has been classified as an AmpH-type class C LMM PBP, a group closely related to AmpC β-lactamases. AmpH has been associated with PG recycling, although its enzymatic activity remained uncharacterized until now. Construction and purification of His-tagged AmpH from E. coli permitted a detailed study of its enzymatic properties. The N-terminal export signal of AmpH is processed, but the protein remains membrane associated. The PBP nature of AmpH was demonstrated by its ability to bind the β-lactams Bocillin FL (a fluorescent penicillin) and cefmetazole. In vitro assays with AmpH and specific muropeptides demonstrated that AmpH is a bifunctional DD-endopeptidase and DD-carboxypeptidase. Indeed, the enzyme cleaved the cross-linked dimers tetrapentapeptide (D45) and tetratetrapeptide (D44) with efficiencies (k(cat)/K(m)) of 1,200 M(-1) s(-1) and 670 M(-1) s(-1), respectively, and removed the terminal D-alanine from muropeptides with a C-terminal D-Ala-D-Ala dipeptide. Both DD-peptidase activities were inhibited by 40 μM cefmetazole. AmpH also displayed a weak β-lactamase activity for nitrocefin of 1.4 × 10(-3) nmol/μg protein/min, 1/1,000 the rate obtained for AmpC under the same conditions. AmpH was also active on purified sacculi, exhibiting the bifunctional character that was seen with pure muropeptides. The wide substrate spectrum of the DD-peptidase activities associated with AmpH supports a role for this protein in PG remodeling or recycling.

  3. Genetics Home Reference: D-bifunctional protein deficiency

    Science.gov (United States)

    ... any developmental skills. Some may reach very early developmental milestones such as the ability to follow movement with their eyes or control their head movement, but they experience a gradual loss of these skills (developmental regression) within a few months. As the condition ...

  4. Synthesis of ZnS:Mn–Fe3O4 bifunctional nanoparticles by inverse microemulsion method

    Directory of Open Access Journals (Sweden)

    Chu Tien Dung

    2016-06-01

    Full Text Available ZnS:Mn–Fe3O4 bifunctional nanoparticles were synthesized by inverse microemulsion method for biomedicine applications. The bifunctional nanoparticles were combined from prepared ZnS:Mn and Fe3O4 nanoparticles in a SiO2 cover matrix. Results show that bifunctional nanoparticles, apart from exhibiting magnetism, have photoluminescence properties, which support the applications targeting biomedicine fluorescent diagnostics as well as magnetic cell sorting or drug delivery.

  5. Preparation of a Versatile Bifunctional Zeolite for Targeted Imaging Applications

    Science.gov (United States)

    Ndiege, Nicholas; Raidoo, Renugan; Schultz, Michael K.; Larsen, Sarah

    2011-01-01

    Bifunctional zeolite Y was prepared for use in targeted in vivo molecular imaging applications. The strategy involved functionalization of the external surface of zeolite Y with chloropropyltriethoxysilane followed by reaction with sodium azide to form azide-functionalized NaY, which is amenable to copper(1) catalyzed click chemistry. In this study, a model alkyne (4-pentyn-1-ol) was attached to the azide-terminated surface via click chemistry to demonstrate feasibility for attachment of molecular targeting vectors (e.g., peptides, aptamers) to the zeolite surface. The modified particle efficiently incorporates the imaging radioisotope gallium-68 (68Ga) into the pores of the azide-functionalized NaY zeolite to form a stable bifunctional molecular targeting vector. The result is a versatile “clickable” zeolite platform that can be tailored for future in vivo molecular targeting and imaging modalities. PMID:21306141

  6. The aminoindanol core as a key scaffold in bifunctional organocatalysts

    Directory of Open Access Journals (Sweden)

    Isaac G. Sonsona

    2016-03-01

    Full Text Available The 1,2-aminoindanol scaffold has been found to be very efficient, enhancing the enantioselectivity when present in organocatalysts. This may be explained by its ability to induce a bifunctional activation of the substrates involved in the reaction. Thus, it is easy to find hydrogen-bonding organocatalysts ((thioureas, squaramides, quinolinium thioamide, etc. in the literature containing this favored structural core. They have been successfully employed in reactions such as Friedel–Crafts alkylation, Michael addition, Diels–Alder and aza-Henry reactions. However, the 1,2-aminoindanol core incorporated into proline derivatives has been scarcely explored. Herein, the most representative and illustrative examples are compiled and this review will be mainly focused on the cases where the aminoindanol moiety confers bifunctionality to the organocatalysts.

  7. Synthesis of novel camphor-derived bifunctional thiourea organocatalysts.

    Science.gov (United States)

    Ričko, Sebastijan; Golobič, Amalija; Svete, Jurij; Stanovnik, Branko; Grošelj, Uroš

    2015-01-01

    Synthesis and catalyst performance of 2,3- (types and ) and 2,8-disubstituted (type ) thiourea bifunctional organocatalysts was attempted. The synthesis of catalyst of type has, so far, not been realized, while catalysts of type , i.e., the 2,3-exo- and the 2-endo-3-exo-thiourea catalysts, were prepared in six steps starting from (+)-camphor. The catalysts of type were prepared from (+)-camphor in eight steps. All the potential catalysts as well as most of the intermediate products were carefully structurally characterized. The thiourea bifunctional organocatalysts were tested in a model reaction of Michael addition of dimethyl malonate to trans-β-nitrostyrene. © 2014 Wiley Periodicals, Inc.

  8. Synthesis of Bifunctional Azobenzene Glycoconjugates for Cysteine-Based Photosensitive Cross-Linking with Bioactive Peptides.

    Science.gov (United States)

    Müller, Anne; Kobarg, Hauke; Chandrasekaran, Vijayanand; Gronow, Joana; Sönnichsen, Frank D; Lindhorst, Thisbe K

    2015-09-21

    Azobenzene linker molecules can be utilized to control peptide/protein function when they are ligated to appropriately spaced amino acid side chains of the peptide. This is because the photochemical E/Z isomerization of the azobenzene N=N double bond allows to switch peptide conformation between folded and unfolded. In this context, we have introduced carbohydrate-functionalized azobenzene derivatives in order to advance the biocompatible properties of azobenzene peptide linkers. Chloroacetamide-functionalized and O-allylated carbohydrate derivatives were synthesized and conjugated with azobenzene to achieve new bifunctional cross-linkers, in order to allow ligation to cysteine side chains by nucleophilic substitution or thiol-ene reaction, respectively. The photochromic properties of the new linker glycoconjugates were determined and first ligation reactions performed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Targeting Prostate Cancer with Bifunctional Modulators of the Androgen Receptor

    Science.gov (United States)

    2015-06-01

    molecules showed only a small (ɝ-fold) attenuation inK for both HDACl and HDAC3, consistent with data in the literature.14 󈧓 For PD106, we examined...cascades, posttranslational modifications (8, 9), and uniquely, small cell- permeable ligands that bind to the LBD (Figure 1A). The canonical mode of...despite the presence of the linker and FK506 moiety, the bifunctional ligands remain cell permeable and retain full efficacy, reveal- ing a

  10. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    Science.gov (United States)

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2015-12-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites. Here we show for a bifunctional catalyst—comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder—that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.

  11. Room Temperature Hydrosilylation of Silicon Nanocrystals with Bifunctional Terminal Alkenes

    Science.gov (United States)

    Yu, Yixuan; Hessel, Colin M.; Bogart, Timothy; Panthani, Matthew G.; Rasch, Michael R.; Korgel, Brian A.

    2013-01-01

    H-terminated Si nanocrystals undergo room temperature hydrosilylation with bifunctional alkenes with distal polar moieties—ethyl-, methyl-ester or carboxylic acids—without the aid of light or added catalyst. The passivated Si nanocrystals exhibit bright photoluminescence (PL) and disperse in polar solvents, including water. We propose a reaction mechanism in which ester or carboxylic acid groups facilitate direct nucleophilic attack of the highly curved Si surface of the nanocrystals by the alkene. PMID:23312033

  12. Design and Synthesis of Bifunctional Oxime Reactivators of OP- inhibited Cholinesterase

    Science.gov (United States)

    2013-08-01

    Oxime Reactivators of OP- inhibited Cholinesterases PRINCIPAL INVESTIGATOR: John T. Koh, Ph.D. CONTRACTING ORGANIZATION...Annual 3. DATES COVERED 08 August 2012-07 August 2013 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Design and synthesis of bifunctional oxime ...feasibly of synthesizing two new classes of oxime reactivators that use bifunctional catalysis to enhance kinetics and improve bioavailability. The

  13. Dimerization and Bifunctionality Confer Robustness to the Isocitrate Dehydrogenase Regulatory System in Escherichia coli*

    Science.gov (United States)

    Dexter, Joseph P.; Gunawardena, Jeremy

    2013-01-01

    An important goal of systems biology is to develop quantitative models that explain how specific molecular features give rise to systems-level properties. Metabolic and regulatory pathways that contain multifunctional proteins are especially interesting to study from this perspective because they have frequently been observed to exhibit robustness: the ability for a system to perform its proper function even as levels of its components change. In this study, we use extensive biochemical data and algebraic modeling to develop and analyze a model that shows how robust behavior arises in the isocitrate dehydrogenase (IDH) regulatory system of Escherichia coli, which was shown in 1985 to experimentally exhibit robustness. E. coli IDH is regulated by reversible phosphorylation catalyzed by the bifunctional isocitrate dehydrogenase kinase/phosphatase (IDHKP), and the level of IDH activity determines whether carbon flux is directed through the glyoxylate bypass (for growth on two-carbon substrates) or the full tricarboxylic acid cycle. Our model, which incorporates recent structural data on IDHKP, identifies several specific biochemical features of the system (including homodimerization of IDH and bifunctionality of IDHKP) that provide a potential explanation for robustness. Using algebraic techniques, we derive an invariant that summarizes the steady-state relationship between the phospho-forms of IDH. We use the invariant in combination with kinetic data on IDHKP to calculate IDH activity at a range of total IDH levels and find that our model predicts robustness. Our work unifies much of the known biochemistry of the IDH regulatory system into a single quantitative framework and highlights the importance of constructing biochemically realistic models in systems biology. PMID:23192354

  14. Bifunctional phosphoglucose/phosphomannose isomerases from the Archaea Aeropyrum pernix and Thermoplasma acidophilum constitute a novel enzyme family within the phosphoglucose isomerase superfamily.

    Science.gov (United States)

    Hansen, Thomas; Wendorff, Daniel; Schönheit, Peter

    2004-01-16

    The hyperthermophilic crenarchaeon Aeropyrum pernix contains phosphoglucose isomerase (PGI) activity. However, obvious homologs with significant identity to known PGIs could not be identified in the sequenced genome of this organism. The PGI activity from A. pernix was purified and characterized. Kinetic analysis revealed that, unlike all known PGIs, the enzyme catalyzed reversible isomerization not only of glucose 6-phosphate but also of epimeric mannose 6-phosphate at similar catalytic efficiency, thus defining the protein as bifunctional phosphoglucose/phosphomannose isomerase (PGI/PMI). The gene pgi/pmi encoding PGI/PMI (open reading frame APE0768) was identified by matrix-assisted laser desorption ionization time-of-flight analyses; the gene was overexpressed in Escherichia coli as functional PGI/PMI. Putative PGI/PMI homologs were identified in several (hyper)thermophilic archaea and two bacteria. The homolog from Thermoplasma acidophilum (Ta1419) was overexpressed in E. coli, and the recombinant enzyme was characterized as bifunctional PGI/PMI. PGI/PMIs showed low sequence identity to the PGI superfamily and formed a distinct phylogenetic cluster. However, secondary structure predictions and the presence of several conserved amino acids potentially involved in catalysis indicate some structural and functional similarity to the PGI superfamily. Thus, we propose that bifunctional PGI/PMI constitutes a novel protein family within the PGI superfamily.

  15. A bifunctional perovskite catalyst for oxygen reduction and evolution.

    Science.gov (United States)

    Jung, Jae-Il; Jeong, Hu Young; Lee, Jang-Soo; Kim, Min Gyu; Cho, Jaephil

    2014-04-25

    La0.3(Ba0.5Sr0.5)0.7Co0.8Fe0.2O3d is a promising bifunctional perovskite catalyst for the oxygen reduction reaction and the oxygen evolution reaction. This catalyst has circa 10 nm-scale rhombohedral LaCoO3 cobaltite particles distributed on the surface. The dynamic microstructure phenomena are attributed to the charge imbalance from the replacement of A-site cations with La3+ and local stress on Cosite sub-lattice with the cubic perovskite structure.

  16. Bifunctional xylanases and their potential use in biotechnology

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, R.; Numan, M.Th.

    is half as sweet as sucrose, can be applicable to foods as a sweetener that is capable of improving diabetic symptoms [37]. Concluding remarks This review provides the information on most of the aspects of bifunctional enzyme with special reference... production. Dev Ind Microbiol 30:53–69 36. Imaizumi K, Nakatsu Y, Sato M, Sedarnawati Y, Sugano M (1991) EVects of xylooligosaccharides on blood glucose, serum and liver lipids and cecum short-chain fatty acids in diabetic rats. Agric Biol Chem 55:199–205 37...

  17. Enantioselective Iodolactonization of Disubstituted Olefinic Acids Using a Bifunctional Catalyst

    Science.gov (United States)

    Fang, Chao; Paull, Daniel H.; Hethcox, J. Caleb; Shugrue, Christopher R.; Martin, Stephen F.

    2012-01-01

    The enantioselective iodolactonizations of a series of diversely-substituted olefinic carboxylic acids are promoted by a BINOL-derived, bifunctional catalyst. Reactions involving 5-alkyl- and 5-aryl-4(Z)-pentenoic acids and 6-alkyl- and 6-aryl-5(Z)-hexenoic acids provide the corresponding γ- and δ-lactones having stereogenic C–I bonds in excellent yields and >97:3 er. Significantly, this represents the first organocatalyst that promotes both bromo- and iodolactonization with high enantioselectivities. The potential of this catalyst to induce kinetic resolutions of racemic unsaturated acids is also demonstrated. PMID:23199100

  18. NSs encoded by groundnut bud necrosis virus is a bifunctional enzyme.

    Directory of Open Access Journals (Sweden)

    Bhushan Lokesh

    Full Text Available Groundnut bud necrosis virus (GBNV, a member of genus Tospovirus in the family Bunyaviridae, infects a large number of leguminosae and solanaceae plants in India. With a view to elucidate the function of nonstructural protein, NSs encoded by the small RNA genome (S RNA, the NSs protein of GBNV- tomato (Karnataka was over-expressed in E. coli and purified by Ni-NTA chromatography. The purified rNSs protein exhibited an RNA stimulated NTPase activity. Further, this activity was metal ion dependent and was inhibited by adenosine 5' (beta, gamma imido triphosphate, an ATP analog. The rNSs could also hydrolyze dATP. Interestingly, in addition to the NTPase and dATPase activities, the rNSs exhibited ATP independent 5' RNA/DNA phosphatase activity that was completely inhibited by AMP. The 5' alpha phosphate could be removed from ssDNA, ssRNA, dsDNA and dsRNA thus confirming that rNSs has a novel 5' alpha phosphatase activity. K189A mutation in the Walker motif A (GxxxxGKT resulted in complete loss of ATPase activity, but the 5' phosphatase activity was unaffected. On the other hand, D159A mutation in the Walker motif B (DExx resulted in partial loss of both the activities. These results demonstrate for the first time that NSs is a bifunctional enzyme, which could participate in viral movement, replication or in suppression of the host defense mechanism.

  19. Novel magnetic-fluorescent bifunctional Janus nanofiber membrane.

    Science.gov (United States)

    Wang, Qiutong; Geng, Yuting; Li, Jianhao; Yin, Meizhen; Hu, Yiseng; Liu, Yangxiu; Pan, Kai

    2018-01-24

    Magnetic-fluorescent bifunctional materials have received global attention owing to the potential in many fields. Herein, we reported a novel magnetic-fluorescent bifunctional Janus nanofiber membrane (NFM) by adding the as-prepared magnetic CoFe2O4 nanoparticles into the polyacrylonitrile (PAN) side (m-PAN) and the fluorescent molecules of 1,8-naphthalene anhydride (1,8-NAD) into the polyvinylpyrrolidone (PVP) side (f-PVP) via electrospinning method. The obtained m-PAN/f-PVP Janus NFM exhibited excellent magnetic performance and high fluorescent property due to the unique structure. Compared with the m-PAN/f-PVP composite NFM, the Janus NFM showed higher fluorescent performance because the fluorescent molecules were isolated from the magnetic nanoparticles. In addition, the Janus NFM not only maintain the good self-supporting state in water but also realize a directional movement attracted by a magnet. The unique structure of Janus nanofiber is of great importance and demonstrates great potential applications. © 2018 IOP Publishing Ltd.

  20. Therapeutic potential of a non-steroidal bifunctional anti-inflammatory and anti-cholinergic agent against skin injury induced by sulfur mustard

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yoke-Chen; Wang, James D.; Hahn, Rita A.; Gordon, Marion K.; Joseph, Laurie B. [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States); Heck, Diane E. [Department of Environmental Science, New York Medical College, Valhalla, NY (United States); Heindel, Ned D. [Department of Chemistry, Lehigh University, Bethlehem, PA (United States); Young, Sherri C. [Department of Chemistry, Muhlenberg College, Allentown, PA (United States); Sinko, Patrick J. [Department of Pharmaceutics, Rutgers University, Piscataway, NJ (United States); Casillas, Robert P. [MRIGlobal, Kansas City, MO (United States); Laskin, Jeffrey D. [Environmental and Occupational Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ (United States); Laskin, Debra L. [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States); Gerecke, Donald R., E-mail: gerecke@eohsi.rutgers.edu [Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ (United States)

    2014-10-15

    Sulfur mustard (bis(2-chloroethyl) sulfide, SM) is a highly reactive bifunctional alkylating agent inducing edema, inflammation, and the formation of fluid-filled blisters in the skin. Medical countermeasures against SM-induced cutaneous injury have yet to be established. In the present studies, we tested a novel, bifunctional anti-inflammatory prodrug (NDH 4338) designed to target cyclooxygenase 2 (COX2), an enzyme that generates inflammatory eicosanoids, and acetylcholinesterase, an enzyme mediating activation of cholinergic inflammatory pathways in a model of SM-induced skin injury. Adult SKH-1 hairless male mice were exposed to SM using a dorsal skin vapor cup model. NDH 4338 was applied topically to the skin 24, 48, and 72 h post-SM exposure. After 96 h, SM was found to induce skin injury characterized by edema, epidermal hyperplasia, loss of the differentiation marker, keratin 10 (K10), upregulation of the skin wound marker keratin 6 (K6), disruption of the basement membrane anchoring protein laminin 322, and increased expression of epidermal COX2. NDH 4338 post-treatment reduced SM-induced dermal edema and enhanced skin re-epithelialization. This was associated with a reduction in COX2 expression, increased K10 expression in the suprabasal epidermis, and reduced expression of K6. NDH 4338 also restored basement membrane integrity, as evidenced by continuous expression of laminin 332 at the dermal–epidermal junction. Taken together, these data indicate that a bifunctional anti-inflammatory prodrug stimulates repair of SM induced skin injury and may be useful as a medical countermeasure. - Highlights: • Bifunctional anti-inflammatory prodrug (NDH4338) tested on SM exposed mouse skin • The prodrug NDH4338 was designed to target COX2 and acetylcholinesterase. • The application of NDH4338 improved cutaneous wound repair after SM induced injury. • NDH4338 treatment demonstrated a reduction in COX2 expression on SM injured skin. • Changes of skin repair

  1. A novel bifunctional hybrid with marine bacterium alkaline phosphatase and Far Eastern holothurian mannan-binding lectin activities.

    Directory of Open Access Journals (Sweden)

    Larissa Balabanova

    Full Text Available A fusion between the genes encoding the marine bacterium Cobetia marina alkaline phosphatase (CmAP and Far Eastern holothurian Apostichopus japonicus mannan-binding C-type lectin (MBL-AJ was performed. Expression of the fusion gene in E. coli cells resulted in yield of soluble recombinant chimeric protein CmAP/MBL-AJ with the high alkaline phosphatase activity and specificity of the lectin MBL-AJ. The bifunctional hybrid CmAP/MBL-AJ was produced as a dimer with the molecular mass of 200 kDa. The CmAP/MBL-AJ dimer model showed the two-subunit lectin part that is associated with two molecules of alkaline phosphatase functioning independently from each other. The highly active CmAP label genetically linked to MBL-AJ has advantaged the lectin-binding assay in its sensitivity and time. The double substitution A156N/F159K in the lectin domain of CmAP/MBL-AJ has enhanced its lectin activity by 25 ± 5%. The bifunctional hybrid holothurian's lectin could be promising tool for developing non-invasive methods for biological markers assessment, particularly for improving the MBL-AJ-based method for early detection of a malignant condition in cervical specimens.

  2. The Mycobacterium tuberculosis Rv2540c DNA sequence encodes a bifunctional chorismate synthase

    Directory of Open Access Journals (Sweden)

    Santos Diógenes S

    2008-04-01

    Full Text Available Abstract Background The emergence of multi- and extensively-drug resistant Mycobacterium tuberculosis strains has created an urgent need for new agents to treat tuberculosis (TB. The enzymes of shikimate pathway are attractive targets to the development of antitubercular agents because it is essential for M. tuberculosis and is absent from humans. Chorismate synthase (CS is the seventh enzyme of this route and catalyzes the NADH- and FMN-dependent synthesis of chorismate, a precursor of aromatic amino acids, naphthoquinones, menaquinones, and mycobactins. Although the M. tuberculosis Rv2540c (aroF sequence has been annotated to encode a chorismate synthase, there has been no report on its correct assignment and functional characterization of its protein product. Results In the present work, we describe DNA amplification of aroF-encoded CS from M. tuberculosis (MtCS, molecular cloning, protein expression, and purification to homogeneity. N-terminal amino acid sequencing, mass spectrometry and gel filtration chromatography were employed to determine identity, subunit molecular weight and oligomeric state in solution of homogeneous recombinant MtCS. The bifunctionality of MtCS was determined by measurements of both chorismate synthase and NADH:FMN oxidoreductase activities. The flavin reductase activity was characterized, showing the existence of a complex between FMNox and MtCS. FMNox and NADH equilibrium binding was measured. Primary deuterium, solvent and multiple kinetic isotope effects are described and suggest distinct steps for hydride and proton transfers, with the former being more rate-limiting. Conclusion This is the first report showing that a bacterial CS is bifunctional. Primary deuterium kinetic isotope effects show that C4-proS hydrogen is being transferred during the reduction of FMNox by NADH and that hydride transfer contributes significantly to the rate-limiting step of FMN reduction reaction. Solvent kinetic isotope effects and

  3. Bifunctional chelates of RH-105 and AU199 as potential radiotherapeutic agents

    Energy Technology Data Exchange (ETDEWEB)

    Droege, P.

    1997-03-01

    Research is presented on new bifunctional chelating ligand systems with stability on the macroscopic and radiochemical levels. The synthesis of the following complexes are described: rhodium 105, palladium 109, and gold 198.

  4. Mono- and bi-functional arenethiols as surfactants for gold nanoparticles: synthesis and characterization

    National Research Council Canada - National Science Library

    Vitale, Floriana; Fratoddi, Ilaria; Battocchio, Chiara; Piscopiello, Emanuela; Tapfer, Leander; Russo, Maria Vittoria; Polzonetti, Giovanni; Giannini, Cinzia

    2011-01-01

    Stable gold nanoparticles stabilized by different mono and bi-functional arenethiols, namely, benzylthiol and 1,4-benzenedimethanethiol, have been prepared by using a modified Brust's two-phase synthesis...

  5. Chemoselective Reactivity of Bifunctional Cyclooctynes on Si(001)

    CERN Document Server

    Reutzel, Marcel; Lipponer, Marcus A; Länger, Christian; Höfer, Ulrich; Koert, Ulrich; Dürr, Michael

    2016-01-01

    Controlled organic functionalization of silicon surfaces as integral part of semiconductor technology offers new perspectives for a wide range of applications. The high reactivity of the silicon dangling bonds, however, presents a major hindrance for the first basic reaction step of such a functionalization, i.e., the chemoselective attachment of bifunctional organic molecules on the pristine silicon surface. We overcome this problem by employing cyclooctyne as the major building block of our strategy. Functionalized cyclooctynes are shown to react on Si(001) selectively via the strained cyclooctyne triple bond while leaving the side groups intact. The achieved selectivity originates from the distinctly different adsorption dynamics of the separate functionalities: A direct adsorption pathway is demonstrated for cyclooctyne as opposed to the vast majority of other organic functional groups. The latter ones react on Si(001) via a metastable intermediate which makes them effectively unreactive in competition wi...

  6. Immobilization of β-glucosidase on bifunctional periodic mesoporous organosilicas.

    Science.gov (United States)

    Guan, Liye; Di, Bin; Su, Mengxiang; Qian, Jie

    2013-08-01

    The aminopropyl-functionalized ethane-bridged bifunctional periodic mesoporous organosilicas (APEPMOs) were synthesized by the co-condensation of 1,2-bis (triethoxysilyl) ethane and 3-aminopropyltriethoxysilane in the presence of cationic surfactants octadecyltrimethylammonium chloride in basic medium. The pores of the APEPMOs were expanded with N,N-dimethyldecylamine and the pore-expanded materials were utilized as supports for β-glucosidase immobilization. A high enzyme loading of 120 mg per g support was achieved in 18 h, and 95.5 % of enzymatic activity was retained. β-Glucosidases were strongly immobilized on APEPMOs with only 5 % desorption in the washing step with buffer solution. The immobilized enzyme had 75 % activity after 20 batch reactions and had improved thermal stability, relative to the free enzyme. These results demonstrate that APEPMOs would be promising supports for β-glucosidases immobilization.

  7. GSK-3: A Bifunctional Role in Cell Death Pathways

    Directory of Open Access Journals (Sweden)

    Keith M. Jacobs

    2012-01-01

    Full Text Available Although glycogen synthase kinase-3 beta (GSK-3β was originally named for its ability to phosphorylate glycogen synthase and regulate glucose metabolism, this multifunctional kinase is presently known to be a key regulator of a wide range of cellular functions. GSK-3β is involved in modulating a variety of functions including cell signaling, growth metabolism, and various transcription factors that determine the survival or death of the organism. Secondary to the role of GSK-3β in various diseases including Alzheimer’s disease, inflammation, diabetes, and cancer, small molecule inhibitors of GSK-3β are gaining significant attention. This paper is primarily focused on addressing the bifunctional or conflicting roles of GSK-3β in both the promotion of cell survival and of apoptosis. GSK-3β has emerged as an important molecular target for drug development.

  8. NHS-MAS{sub 3}: a bifunctional chelator alternative to NHS-MAG{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Chang, F.; Qu, T.; Rusckowski, M.; Hnatowich, D.J

    1999-04-01

    This laboratory uses an N-hydroxysuccinimide derivative of S-acetylmercaptoacetyltriglycine (NHS-MAG{sub 3}) to conjugate amines for subsequent labeling with {sup 99m}Tc. However, the synthesis from triglycerine is general and not restricted to this tripeptide. We had earlier selected a small number of alternative tripeptides and synthesized the corresponding NHS derivatives. Each was then evaluated in a search for bifunctional chelators with properties superior to NHS-MAG{sub 3}, such as lower serum protein binding or improved stability to cysteine challenge. Based on these preliminary results, NHS-S-acetylmercaptoacetyltriserine (NHS-MAS{sub 3}) was selected for further investigation. We have now conjugated this bifunctional chelator to biocytin and to an amine-derivatized peptide nucleic acid (PNA). Both carriers were also conjugated with NHS-MAG{sub 3} under identical conditions and all were labeled with {sup 99m}Tc at neutral pH and at boiling temperature while the conjugated PNAs were radiolabelled at neutral pH and at room temperature. Regardless of the chelator, reverse phase HPLC radiochromatograms of the labeled biotins and PNAs after purification showed a single peak. However, by size exclusion HPLC, the radiochromatograms always showed several peaks even after purification, but the MAS{sub 3} radiochromatograms were less complicated. For biotin and PNA both, radiolabeling via MAS{sub 3} showed improved {sup 99m}Tc stability in 37 deg. C serum and in cysteine solution. The four preparations were administered to mice implanted in one thigh with avidin beads (biotins) or complementary PNA beads (PNAs). At 5 h post-administration, no significant differences were observed in the targeting of PNA beads between the two chelators, however the target thigh/normal thigh ratio was significantly higher for MAS{sub 3}-biotin compared to MAG{sub 3}-biotin. We conclude that labeling biocytin and amine-derivatized PNA with NHS-MAS{sub 3} compared to NHS-MAG{sub 3

  9. Bifunctional lacZ alpha-ccdB genes for selective cloning of PCR products.

    Science.gov (United States)

    Gabant, P; Drèze, P L; Van Reeth, T; Szpirer, J; Szpirer, C

    1997-11-01

    The use of PCR-amplified DNA-fragments is a classical approach to generate recombinant DNA. To facilitate the cloning of PCR products, we have constructed two new pKIL vectors that allow selection of recombinants. The multiple cloning sites (MCS) of these plasmids contain two adjacent Aspel sites and a unique HindII site. Cleavage of these vectors with Aspel produce linearized molecules with a single thymidine nucleotide at the 3' ends allowing TA cloning of Taq-amplified fragments. On the other hand, cleavage with HindII can be used for the cloning of blunt-ended PCR products generated by other DNA polymerases. The LacZ alpha-CcdB fusion protein produced by these plasmids has retained both the CcdB killer activity and the ability to alpha-complement the truncated LacZ delta M15. This bifunctionality allowed us to show that small PCR products (< 1000 bp) that do not disrupt lacZ alpha efficiently do inactivate CcdB, which demonstrates that the CcdB-based selection is well adapted for cloning of PCR products, especially for small size fragments.

  10. First report of a bifunctional chitinase/lysozyme produced by Bacillus pumilus SG2.

    Science.gov (United States)

    Ghasemi, Seyedhadi; Ahmadian, Gholamreza; Sadeghi, Mehdi; Zeigler, Daniel R; Rahimian, Heshmatollah; Ghandili, Soheila; Naghibzadeh, Neda; Dehestani, Ali

    2011-03-07

    Bacillus pumilus SG2 isolated from high salinity ecosystem in Iran produces two chitinases (ChiS and ChiL) and secretes them into the medium. In this study, chiS and chiL genes were cloned in pQE-30 expression vector and were expressed in the cytoplasm of Escherichia coli strain M15. The recombinant proteins were purified using Ni-NTA column. The optimum pH and optimum temperature for enzyme activity of ChiS were pH 6, 50°C; those of ChiL were pH 6.5, 40°C. The purified chitinases showed antifungal activity against Fusarium graminearum, Rhizoctonia solani, Magnaporthe grisea, Sclerotinia sclerotiorum, Trichoderma reesei, Botrytis cinerea and Bipolaris sp. Moreover, purified ChiS was identified as chitinase/lysozyme, which are capable of degrading the chitin component of fungal cell walls and the peptidoglycan component of cell walls with many kinds of bacteria (Xanthomonas translucens pv. hordei, Xanthomonas axonopodis pv. citri, Bacillus licheniformis, E. coli C600, E. coli TOP10, Pseudomonas aeruginosa and Pseudomonas putida). Strong homology was found between the three-dimensional structures of ChiS and a chitinase/lysozyme from Bacillus circulans WL-12. This is the first report of a bifunctional chitinase/lysozyme from B. pumilus. Copyright © 2010 Elsevier Inc. All rights reserved.

  11. The bifunctional dihydrofolate reductase thymidylate synthase of Tetrahymena thermophila provides a tool for molecular and biotechnology applications

    Directory of Open Access Journals (Sweden)

    Tiedtke Arno

    2006-03-01

    Full Text Available Abstract Background Dihydrofolate reductase (DHFR and thymidylate synthase (TS are crucial enzymes in DNA synthesis. In alveolata both enzymes are expressed as one bifunctional enzyme. Results Loss of this essential enzyme activities after successful allelic assortment of knock out alleles yields an auxotrophic marker in ciliates. Here the cloning, characterisation and functional analysis of Tetrahymena thermophila's DHFR-TS is presented. A first aspect of the presented work relates to destruction of DHFR-TS enzyme function in an alveolate thereby causing an auxotrophy for thymidine. A second aspect is to knock in an expression cassette encoding for a foreign gene with subsequent expression of the target protein. Conclusion This system avoids the use of antibiotics or other drugs and therefore is of high interest for biotechnological applications.

  12. Bioinspired Bifunctional Membrane for Efficient Clean Water Generation.

    Science.gov (United States)

    Liu, Yang; Lou, Jinwei; Ni, Mengtian; Song, Chengyi; Wu, Jianbo; Dasgupta, Neil P; Tao, Peng; Shang, Wen; Deng, Tao

    2016-01-13

    Solving the problems of water pollution and water shortage is an urgent need for the sustainable development of modern society. Different approaches, including distillation, filtration, and photocatalytic degradation, have been developed for the purification of contaminated water and the generation of clean water. In this study, we explored a new approach that uses solar light for both water purification and clean water generation. A bifunctional membrane consisting of a top layer of TiO2 nanoparticles (NPs), a middle layer of Au NPs, and a bottom layer of anodized aluminum oxide (AAO) was designed and fabricated through multiple filtration processes. Such a design enables both TiO2 NP-based photocatalytic function and Au NP-based solar-driven plasmonic evaporation. With the integration of these two functions into a single membrane, both the purification of contaminated water through photocatalytic degradation and the generation of clean water through evaporation were demonstrated using simulated solar illumination. Such a demonstration should also help open up a new strategy for maximizing solar energy conversion and utilization.

  13. Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

    Science.gov (United States)

    Sheng, Shujuan; Ma, Qianli; Dong, Xiangting; Lv, Nan; Wang, Jinxian; Yu, Wensheng; Liu, Guixia

    2015-02-01

    In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3)  S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials. Copyright © 2014 John Wiley & Sons, Ltd.

  14. Mechanish of dTTP Inhibition of the Bifunctional dCTP Deaminase:dUTPase Encoded by Mycobacterium tuberculosis

    DEFF Research Database (Denmark)

    Helt, Signe Smedegaard; Thymark, Majbritt; Harris, Pernille

    2008-01-01

    Recombinant deoxycytidine triphosphate (dCTP) deaminase from Mycobacterium tuberculosis was produced in Escherichia coli and purified. The enzyme proved to be a bifunctional dCTP deaminase:deoxyuridine triphosphatase. As such, the M. tuberculosis enzyme is the second bifunctional enzyme...

  15. Bifunctional ectodermal stem cells around the nail display dual fate homeostasis and adaptive wounding response toward nail regeneration.

    Science.gov (United States)

    Leung, Yvonne; Kandyba, Eve; Chen, Yi-Bu; Ruffins, Seth; Chuong, Cheng-Ming; Kobielak, Krzysztof

    2014-10-21

    Regulation of adult stem cells (SCs) is fundamental for organ maintenance and tissue regeneration. On the body surface, different ectodermal organs exhibit distinctive modes of regeneration and the dynamics of their SC homeostasis remain to be unraveled. A slow cycling characteristic has been used to identify SCs in hair follicles and sweat glands; however, whether a quiescent population exists in continuously growing nails remains unknown. Using an in vivo label retaining cells (LRCs) system, we detected an unreported population of quiescent cells within the basal layer of the nail proximal fold, organized in a ring-like configuration around the nail root. These nail LRCs express the hair stem cell marker, keratin 15 (K15), and lineage tracing show that these K15-derived cells can contribute to both the nail structure and peri-nail epidermis, and more toward the latter. Thus, this stem cell population is bifunctional. Upon nail plucking injury, the homeostasis is tilted with these SCs dominantly delivering progeny to the nail matrix and differentiated nail plate, demonstrating their plasticity to adapt to wounding stimuli. Moreover, in vivo engraftment experiments established that transplanted nail LRCs can actively participate in functional nail regeneration. Transcriptional profiling of isolated nail LRCs revealed bone morphogenetic protein signaling favors nail differentiation over epidermal fate. Taken together, we have found a previously unidentified ring-configured population of bifunctional SCs, located at the interface between the nail appendage organ and adjacent epidermis, which physiologically display coordinated homeostatic dynamics but are capable of rediverting stem cell flow in response to injury.

  16. Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Petrie, Jonathan R.; Cooper, Valentino R.; Freeland, John W.; Meyer, Tricia L.; Zhang, Zhiyong; Lutterman, Daniel A.; Lee, Ho Nyung

    2016-03-02

    Strain is known to greatly influence low temperature oxygen electro catalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and Metal-air batteries. However, its catalytic impact on transition-metal oxide thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO3 to systematically determine its influence on both the oxygen reduction and oxygen evolution reaction. Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals' such as Pt. We attribute the improved bifunctionality to strain induced splitting of the e(g) Orbitals, which can customize orbital asymmetry at the surface. Analogous to strain induced shifts in the d-band center of noble metals relative to the Fermi level, :such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active Oxides.

  17. Electrochemical Investigation of Interaction between a Bifunctional Probe and GG Mismatch Duplex.

    Science.gov (United States)

    Li, Jiao; He, Hanping; Peng, Xiaoqian; Huang, Min; Zhang, Xiuhua; Wang, Shengfu

    2015-01-01

    A bifunctional probe (FecNC), containing a recognition part and an electrochemical active center, was applied to electrochemical detection of GG mismatch duplexes. The preparation of gold electrodes modified by mismatch and complementatry duplexes was characterized by electrochemical impedance spectroscopy (EIS) and optimized for better detection in terms of self-assembly time, hybridization time, and incubation time. The interaction between FecNC and DNA duplexes modified on the surface of a gold electrode was explored by square wave voltammetry (SWV) and EIS. The results showed that the DNA duplexes with GG mismatch on the surface of a gold electrode was easily detected by the largest electrochemical signal of the bifunctional probe because of its selective binding to GG mismatches. The bifunctional probe could offer a simple, effective electrochemical detection of GG mismatches, and theoretical bases for development of electrochemical biosensors. Further, the method would be favorable for diagnosis of genetic diseases.

  18. Polymer-Supported Reagents: The Role of Bifunctionality in the Design of Ion-Selective Complexants

    Energy Technology Data Exchange (ETDEWEB)

    Alexandratos, S. D.

    2001-06-01

    The importance of multi-functionality in the preparation of ion-selective polymers is evident from the structure of enzymes where specific metal ions are bound through cooperative interactions among different amino acids. In synthetic polymers, ionic selectivity is enhanced when a chemical reaction is superimposed on an ion-exchange process. The concept of reactive ion exchange has been extended through the synthesis of crosslinked polymers whose metal ion selectivity is a function of reduction, coordination or precipitation reactions as determined by various covalently bound ligands. Development of three classes of dual mechanism bifunctional polymers, a new series of bifunctional diphosphonate polymers, and novel bifunctional ion-selective polymers with enhanced ionic accessibility has been accomplished.

  19. Bifunctional Pt-Si Alloys for Small Organic Molecule Electro-oxidation

    DEFF Research Database (Denmark)

    Permyakova, Anastasia Aleksandrovna; Suntivich, Jin; Han, Binghong

    Designing highly active catalysts for electro-oxidation of small organic molecules can help to reduce the anodic overpotential for more efficient utilization of hydrocarbon fuels. The challenge in developing more active electrocatalysts for electro-oxidation reactions is to satisfy the stringent...... bifunctional requirement, which demands both adsorption and water oxidation sites. In this contribution, we explore the possibility of using Pt-Si alloys to fulfill this bifunctional requirement. Silicon, a highly oxophillic element, is alloyed into Pt as a site for water oxidation, while Pt serves as a CO...

  20. Identification of a novel bifunctional delta12/delta15 fatty acid desaturase from a basidiomycete, Coprinus cinereus TD#822-2.

    Science.gov (United States)

    Zhang, Shuo; Sakuradani, Eiji; Ito, Kuni; Shimizu, Sakayu

    2007-01-23

    A new gene encoding a delta12 fatty acid desaturase-related protein was cloned from a multicellular basidiomycete Coprinus cinereus TD#822-2. The 1326 bp full-length gene, designated as Cop-odeA, codes for a putative protein of 442 amino acids with a MW of 49224. The Cop-odeA yeast transformant accumulated four new fatty acids identified as 9,12-hexadecadienoic acid, 9,12,15-hexadecatrienoic acid, linoleic acid, and alpha-linolenic acid, which comprised 8.8%, 1.0%, 29.0%, and 0.6% of the total fatty acids, respectively. The Cop-odeA protein was confirmed to be a novel bifunctional fatty acid desaturase with both high delta12 desaturase activity and unusual delta15 desaturase activity.

  1. Bifunctional Poly(acrylamide) Hydrogels through Orthogonal Coupling Chemistries.

    Science.gov (United States)

    Farrukh, Aleeza; Paez, Julieta I; Salierno, Marcelo; Fan, Wenqiang; Berninger, Benedikt; Del Campo, Aránzazu

    2017-03-13

    Biomaterials for cell culture allowing simple and quantitative presentation of instructive cues enable rationalization of the interplay between cells and their surrounding microenvironment. Poly(acrylamide) (PAAm) hydrogels are popular 2D-model substrates for this purpose. However, quantitative and reproducible biofunctionalization of PAAm hydrogels with multiple ligands in a trustable, controlled, and independent fashion is not trivial. Here, we describe a method for bifunctional modification of PAAm hydrogels with thiol- and amine- containing biomolecules with controlled densities in an independent, orthogonal manner. We developed copolymer networks of AAm with 9% acrylic acid and 2% N-(4-(5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)phenyl)acrylamide. The covalent binding of thiol- and amine-containing chromophores at tunable concentrations was demonstrated and quantified by UV spectroscopy. The morphology, mechanical properties, and homogeneity of the copolymerized hydrogels were characterized by scanning electron microscopy, dynamic mechanical analysis, and confocal microscopy studies. Our copolymer hydrogels were bifunctionalized with polylysine and a laminin-mimetic peptide using the specific chemistries. We analyzed the effect of binding protocol of the two components in the maturation of cultured postmitotic cortical neurons. Our substrates supported neuronal attachment, proliferation, and neuronal differentiation. We found that neurons cultured on our hydrogels bifunctionalized with ligand-specific chemistries in a sequential fashion exhibited higher maturation at comparable culture times than using a simultaneous bifunctionalization strategy, displaying a higher number of neurites, branches, and dendritic filopodia. These results demonstrate the relevance of quantitative and optimized coupling chemistries for the performance of simple biomaterials and with sensitive cell types.

  2. Characterization of a bifunctional glyoxylate cycle enzyme, malate synthase/isocitrate lyase, of Euglena gracilis.

    Science.gov (United States)

    Nakazawa, Masami; Nishimura, Masaaki; Inoue, Kengo; Ueda, Mitsuhiro; Inui, Hiroshi; Nakano, Yoshihisa; Miyatake, Kazutaka

    2011-01-01

    The glyoxylate cycle is a modified form of the tricarboxylic acid cycle, which enables organisms to synthesize carbohydrates from C2 compounds. In the protozoan Euglena gracilis, the key enzyme activities of the glyoxylate cycle, isocitrate lyase (ICL) and malate synthase (MS), are conferred by a single bifunctional protein named glyoxylate cycle enzyme (Euglena gracilis glyoxylate cycle enzyme [EgGCE]). We analyzed the enzymatic properties of recombinant EgGCE to determine the functions of its different domains. The 62-kDa N-terminal domain of EgGCE was sufficient to provide the MS activity as expected from an analysis of the deduced amino acid sequence. In contrast, expression of the 67-kDa C-terminal domain of EgGCE failed to yield ICL activity even though this domain was structurally similar to ICL family enzymes. Analyses of truncation mutants suggested that the N-terminal residues of EgGCE are critical for both the ICL and MS activities. The ICL activity of EgGCE increased in the presence of micro-molar concentrations of acetyl-coenzyme A (CoA). Acetyl-CoA also increased the activity in a mutant type EgGCE with a mutation at the acetyl-CoA binding site in the MS domain of EgGCE. This suggests that acetyl-CoA regulates the ICL reaction by binding to a site other than the catalytic center of the MS reaction. © 2011 The Author(s). Journal of Eukaryotic Microbiology© 2011 International Society of Protistologists.

  3. Domain Organization in Candida glabrata THI6, a Bifunctional Enzyme Required for Thiamin Biosynthesis in Eukaryotes

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Debamita; Chatterjee, Abhishek; Begley, Tadhg P.; Ealick, Steven E. (Cornell); (TAM)

    2010-11-15

    THI6 is a bifunctional enzyme found in the thiamin biosynthetic pathway in eukaryotes. The N-terminal domain of THI6 catalyzes the ligation of the thiamin thiazole and pyrimidine moieties to form thiamin phosphate, and the C-terminal domain catalyzes the phosphorylation of 4-methyl-5-hydroxyethylthiazole in a salvage pathway. In prokaryotes, thiamin phosphate synthase and 4-methyl-5-hydroxyethylthiazole kinase are separate gene products. Here we report the first crystal structure of a eukaryotic THI6 along with several complexes that characterize the active sites responsible for the two chemical reactions. THI6 from Candida glabrata is a homohexamer in which the six protomers form a cage-like structure. Each protomer is composed of two domains, which are structurally homologous to their monofunctional bacterial counterparts. Two loop regions not found in the bacterial enzymes provide interactions between the two domains. The structures of different protein-ligand complexes define the thiazole and ATP binding sites of the 4-methyl-5-hydroxyethylthiazole kinase domain and the thiazole phosphate and 4-amino-5-hydroxymethyl-2-methylpyrimidine pyrophosphate binding sites of the thiamin phosphate synthase domain. Our structural studies reveal that the active sites of the two domains are 40 {angstrom} apart and are not connected by an obvious channel. Biochemical studies show 4-methyl-5-hydroxyethylthiazole phosphate is a substrate for THI6; however, adenosine diphospho-5{beta}-ethyl-4-methylthiazole-2-carboxylic acid, the product of THI4, is not a substrate for THI6. This suggests that an unidentified enzyme is necessary to produce the substrate for THI6 from the THI4 product.

  4. A bifunctional geranyl and geranylgeranyl diphosphate synthase is involved in terpene oleoresin formation in Picea abies.

    Science.gov (United States)

    Schmidt, Axel; Wächtler, Betty; Temp, Ulrike; Krekling, Trygve; Séguin, Armand; Gershenzon, Jonathan

    2010-02-01

    The conifer Picea abies (Norway spruce) defends itself against herbivores and pathogens with a terpenoid-based oleoresin composed chiefly of monoterpenes (C(10)) and diterpenes (C(20)). An important group of enzymes in oleoresin biosynthesis are the short-chain isoprenyl diphosphate synthases that produce geranyl diphosphate (C(10)), farnesyl diphosphate (C(15)), and geranylgeranyl diphosphate (C(20)) as precursors of different terpenoid classes. We isolated a gene from P. abies via a homology-based polymerase chain reaction approach that encodes a short-chain isoprenyl diphosphate synthase making an unusual mixture of two products, geranyl diphosphate (C(10)) and geranylgeranyl diphosphate (C(20)). This bifunctionality was confirmed by expression in both prokaryotic (Escherichia coli) and eukaryotic (P. abies embryogenic tissue) hosts. Thus, this isoprenyl diphosphate synthase, designated PaIDS1, could contribute to the biosynthesis of both major terpene types in P. abies oleoresin. In saplings, PaIDS1 transcript was restricted to wood and bark, and transcript level increased dramatically after methyl jasmonate treatment, which induces the formation of new (traumatic) resin ducts. Polyclonal antibodies localized the PaIDS1 protein to the epithelial cells surrounding the traumatic resin ducts. PaIDS1 has a close phylogenetic relationship to single-product conifer geranyl diphosphate and geranylgeranyl diphosphate synthases. Its catalytic properties and reaction mechanism resemble those of conifer geranylgeranyl diphosphate synthases, except that significant quantities of the intermediate geranyl diphosphate are released. Using site-directed mutagenesis and chimeras of PaIDS1 with single-product geranyl diphosphate and geranylgeranyl diphosphate synthases, specific amino acid residues were identified that alter the relative composition of geranyl to geranylgeranyl diphosphate.

  5. High surface area carbon for bifunctional air electrodes applied in zinc-air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Arai, H. [on leave from NTT Laboratories (Japan); Mueller, S.; Haas, O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Bifunctional air electrodes with high surface area carbon substrates showed low reduction overpotential, thus are promising for enhancing the energy efficiency and power capability of zinc-air batteries. The improved performance is attributed to lower overpotential due to diffusion of the reaction intermediate, namely the peroxide ion. (author) 1 fig., 2 refs.

  6. Synthesis, characterization and performance of bifunctional catalysts for the synthesis of menthol from citronellal

    NARCIS (Netherlands)

    ten Dam, J.; Ramanathan, A; Djanashvili, K.; Kapteijn, F.; Hanefeld, U.

    2017-01-01

    The synthesis of a series of bifunctional catalysts (1 wt% Pt/W-TUD-1 (Technische Universiteit Delft-1) and 1 wt% Pt/WO3/TUD-1) with different tungsten loadings (5-30 wt% WO3) is described. They were characterized using ICP-OES, INAA, N2 physisorption, XRD and

  7. Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting.

    Science.gov (United States)

    Ling, Chongyi; Shi, Li; Ouyang, Yixin; Zeng, Xiao Cheng; Wang, Jinlan

    2017-08-09

    Nanosheet supported single-atom catalysts (SACs) can make full use of metal atoms and yet entail high selectivity and activity, and bifunctional catalysts can enable higher performance while lowering the cost than two separate unifunctional catalysts. Supported single-atom bifunctional catalysts are therefore of great economic interest and scientific importance. Here, on the basis of first-principles computations, we report a design of the first single-atom bifunctional eletrocatalyst, namely, isolated nickel atom supported on β 12 boron monolayer (Ni 1 /β 12 -BM), to achieve overall water splitting. This nanosheet supported SAC exhibits remarkable electrocatalytic performance with the computed overpotential for oxygen/hydrogen evolution reaction being just 0.40/0.06 V. The ab initio molecular dynamics simulation shows that the SAC can survive up to 800 K elevated temperature, while enacting a high energy barrier of 1.68 eV to prevent isolated Ni atoms from clustering. A viable experimental route for the synthesis of Ni 1 /β 12 -BM SAC is demonstrated from computer simulation. The desired nanosheet supported single-atom bifunctional catalysts not only show great potential for achieving overall water splitting but also offer cost-effective opportunities for advancing clean energy technology.

  8. Bifunctional catalysts for the direct production of liquid fuels from syngas

    NARCIS (Netherlands)

    Sartipi, S.

    2014-01-01

    Design and development of catalyst formulations that maximize the direct production of liquid fuels by combining Fischer-Tropsch synthesis (FTS), hydrocarbon cracking, and isomerization into one single catalyst particle (bifunctional FTS catalyst) have been investigated in this thesis. To achieve

  9. Oxidations of amines with molecular oxygen using bifunctional gold–titania catalysts

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Mentzel, Uffe Vie

    2008-01-01

    Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold–titania c...... new and environmentally benign routes to caprolactam and cyclohexanone oxime, both of which are precursors for nylon-6....

  10. Direct catalytic transformation of carbohydrates into 5-ethoxymethylfurfural with acid–base bifunctional hybrid nanospheres

    DEFF Research Database (Denmark)

    Li, Hu; Khokarale, Santosh Govind; Kotni, Ramakrishna

    2014-01-01

    carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid–base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl...

  11. One-Pot Formation of Functionalized Indole and Benzofuran Derivatives Using a Single Bifunctional Ruthenium Catalyst

    OpenAIRE

    Nair, Reji N.; Lee, Paul J.; Grotjahn, Douglas B

    2010-01-01

    We report a single bifunctional ruthenium catalyst for cyclization of terminal alkynylaryl amines and -phenols to corresponding indole and benzofuran derivatives in good yields. Key features the ability to cyclize and hydrate terminal alkynes in one step and to deuterate the heteroaromatic compounds formed.

  12. Liquid phase in situ hydrodeoxygenation of biomass-derived phenolic compounds to hydrocarbons over bifunctional catalysts

    Science.gov (United States)

    Junfeng Feng; Chung-yun Hse; Zhongzhi Yang; Kui Wang; Jianchun Jiang; Junming Xu

    2017-01-01

    The objective of this study was to find an effective method for converting renewable biomass-derived phenolic compounds into hydrocarbons bio-fuel via in situ catalytic hydrodeoxygenation. The in situ hydrodeoxygenation of biomass-derived phenolic compounds was carried out in methanol-water solvent over bifunctional catalysts of Raney Ni and HZSM-5 or H-Beta. In the in...

  13. Microwave assisted bi-functional activation of -bromo-tert-alcohols

    Indian Academy of Sciences (India)

    A concurrent bi-functional activation of trans-vicinal bromo- and hydroxyl groups with ZnS is elucidated. This is a new observation under microwave and applies to -bromo-tert-alcohols derived from 1,4-disubstitued-1-cyclohexenes. It is very useful in the synthesis of 2,3-unsaturated ketones derived from monoterpenes ...

  14. Comparison of bifunctional chelates for {sup 64}Cu antibody imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Cara L.; Crisp, Sarah; Bensimon, Corinne [MDS Nordion, Vancouver, BC (Canada); Yapp, Donald T.T.; Ng, Sylvia S.W. [British Columbia Cancer Agency Research Centre, Vancouver, BC (Canada); University of British Columba, The Faculty of Pharmaceutical Sciences, Vancouver, BC (Canada); Sutherland, Brent W. [British Columbia Cancer Agency Research Centre, Vancouver, BC (Canada); Gleave, Martin [Prostate Centre at Vancouver General Hospital, Vancouver, BC (Canada); Jurek, Paul; Kiefer, Garry E. [Macrocyclics Inc., Dallas, TX (United States)

    2010-11-15

    Improved bifunctional chelates (BFCs) are needed to facilitate efficient {sup 64}Cu radiolabeling of monoclonal antibodies (mAbs) under mild conditions and to yield stable, target-specific agents. The utility of two novel BFCs, 1-Oxa-4,7,10-triazacyclododecane-5-S-(4-isothiocyanatobenzyl)-4,7,10-triacetic acid (p-SCN-Bn-Oxo-DO3A) and 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-4-S-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (p-SCN-Bn-PCTA), for mAb imaging with {sup 64}Cu were compared to the commonly used S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-tetraacetic acid (p-SCN-Bn-DOTA). The BFCs were conjugated to trastuzumab, which targets the HER2/neu receptor. {sup 64}Cu radiolabeling of the conjugates was optimized. Receptor binding was analyzed using flow cytometry and radioassays. Finally, PET imaging and biodistribution studies were done in mice bearing either HER2/neu-positive or HER2/neu-negative tumors. {sup 64}Cu-Oxo-DO3A- and PCTA-trastuzumab were prepared at room temperature in >95% radiochemical yield (RCY) in <30 min, compared to only 88% RCY after 2 h for the preparation of {sup 64}Cu-DOTA-trastuzumab under the same conditions. Cell studies confirmed that the immunoreactivity of the mAb was retained for each of the bioconjugates. In vivo studies showed that {sup 64}Cu-Oxo-DO3A- and PCTA-trastuzumab had higher uptake than the {sup 64}Cu-DOTA-trastuzumab at 24 h in HER2/neu-positive tumors, resulting in higher tumor to background ratios and better tumor images. By 40 h all three of the {sup 64}Cu-BFC-trastuzumab conjugates allowed for clear visualization of the HER2/neu-positive tumors but not the negative control tumor. The antibody conjugates of PCTA and Oxo-DO3A were shown to have superior {sup 64}Cu radiolabeling efficiency and stability compared to the analogous DOTA conjugate. In addition, {sup 64}Cu-PCTA and Oxo-DO3A antibody conjugates may facilitate earlier imaging with greater target to background ratios than

  15. Selective peptide inhibitors of bifunctional thymidylate synthase-dihydrofolate reductase from Toxoplasma gondii provide insights into domain-domain communication and allosteric regulation.

    Science.gov (United States)

    Landau, Mark J; Sharma, Hitesh; Anderson, Karen S

    2013-09-01

    The bifunctional enzyme thymidylate synthase-dihydrofolate reductase (TS-DHFR) plays an essential role in DNA synthesis and is unique to several species of pathogenic protozoans, including the parasite Toxoplasma gondii. Infection by T. gondii causes the prevalent disease toxoplasmosis, for which TS-DHFR is a major therapeutic target. Here, we design peptides that target the dimer interface between the TS domains of bifunctional T. gondii TS-DHFR by mimicking β-strands at the interface, revealing a previously unknown allosteric target. The current study shows that these β-strand mimetic peptides bind to the apo-enzyme in a species-selective manner to inhibit both the TS and distal DHFR. Fluorescence spectroscopy was used to monitor conformational switching of the TS domain and demonstrate that these peptides induce a conformational change in the enzyme. Using structure-guided mutagenesis, nonconserved residues in the linker between TS and DHFR were identified that play a key role in domain-domain communication and in peptide inhibition of the DHFR domain. These studies validate allosteric inhibition of apo-TS, specifically at the TS-TS interface, as a potential target for novel, species-specific therapeutics for treating T. gondii parasitic infections and overcoming drug resistance. © 2013 The Protein Society.

  16. Bifunctional TaqII restriction endonuclease: redefining the prototype DNA recognition site and establishing the Fidelity Index for partial cleaving

    National Research Council Canada - National Science Library

    Zylicz-Stachula, Agnieszka; Zołnierkiewicz, Olga; Sliwińska, Katarzyna; Jeżewska-Frąckowiak, Joanna; Skowron, Piotr M

    2011-01-01

    The TaqII enzyme is a member of the Thermus sp. enzyme family that we propounded previously within Type IIS restriction endonucleases, containing related thermophilic bifunctional endonucleases-methyltransferases from various Thermus sp...

  17. Asymmetric hydroxyamination of oxindoles catalyzed by chiral bifunctional tertiary amine thiourea: construction of 3-amino-2-oxindoles with quaternary stereocenters.

    Science.gov (United States)

    Jia, Li-Na; Huang, Jun; Peng, Lin; Wang, Liang-Liang; Bai, Jian-Fei; Tian, Fang; He, Guang-Yun; Xu, Xiao-Ying; Wang, Li-Xin

    2012-01-14

    Chiral bifunctional tertiary amine thiourea was applied to catalyze the asymmetric hydroxyamination of 3-subsituted oxindoles with nitrosobenzene to construct 3-amino-2-oxindoles with quaternary stereocenters in good yields (up to 91%) and enantioselectivities (up to 90% ee).

  18. A Metal-Amino Acid Complex-Derived Bifunctional Oxygen Electrocatalyst for Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Ding, Yanjun; Niu, Yuchen; Yang, Jia; Ma, Liang; Liu, Jianguo; Xiong, Yujie; Xu, Hangxun

    2016-10-01

    Bifunctional oxygen electrocatalyst: A metal-amino acid complex is developed to prepare high-performance mesoporous carbon electrocatalyst for both oxygen reduction and oxygen evolution reactions. Such prepared catalyst can be used to assemble rechargeable zinc-air batteries with excellent durability. This work represents a new route toward low-cost, highly active, and durable bifunctional electrocatalysts for cutting-edge energy conversion devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Biochemical Characteristics and Variable Alginate-Degrading Modes of a Novel Bifunctional Endolytic Alginate Lyase.

    Science.gov (United States)

    Cheng, Yuanyuan; Wang, Dandan; Gu, Jingyan; Li, Junge; Liu, Huihui; Li, Fuchuan; Han, Wenjun

    2017-12-01

    Bifunctional alginate lyases can efficiently degrade alginate comprised of mannuronate (M) and guluronate (G), but their substrate-degrading modes have not been thoroughly elucidated to date. In this study, we present Aly1 as a novel bifunctional endolytic alginate lyase of the genus Flammeovirga The recombinant enzyme showed optimal activity at 50°C and pH 6.0. The enzyme produced unsaturated disaccharide (UDP2) and trisaccharide fractions as the final main alginate digests. Primary substrate preference tests and further structure identification of various size-defined final oligosaccharide products demonstrated that Aly1 is a bifunctional alginate lyase and prefers G to M. Tetrasaccharide-size fractions are the smallest substrates, and M, G, and UDP2 fractions are the minimal product types. Remarkably, Aly1 can vary its substrate-degrading modes in accordance with the terminus types, molecular sizes, and M/G contents of alginate substrates, producing a series of small size-defined saturated oligosaccharide products from the nonreducing ends of single or different saturated sugar chains and yielding unsaturated products in distinct but restricted patterns. The action mode changes can be partially inhibited by fluorescent labeling at the reducing ends of oligosaccharide substrates. Deletion of the noncatalytic region (NCR) of Aly1 caused weak changes of biochemical characteristics but increased the degradation proportions of small size-defined saturated M-enriched oligosaccharide substrates and unsaturated tetrasaccharide fractions without any size changes of degradable oligosaccharides, thereby enhancing the M preference and enzyme activity. Therefore, our results provided insight into the variable action mode of a novel bifunctional endolytic alginate lyase to inform accurate enzyme use.IMPORTANCE The elucidated endolytic alginate lyases usually degrade substrates into various size-defined unsaturated oligosaccharide products (≥UDP2), and exolytic enzymes

  20. Biochemical characterization of TyrA enzymes from Ignicoccus hospitalis and Haemophilus influenzae: A comparative study of the bifunctional and monofunctional dehydrogenase forms.

    Science.gov (United States)

    Shlaifer, Irina; Quashie, Peter Kojo; Kim, Hyun Young; Turnbull, Joanne L

    2017-03-01

    Biosynthesis of l-tyrosine (l-Tyr) is directed by the interplay of two enzymes. Chorismate mutase (CM) catalyzes the rearrangement of chorismate to prephenate, which is then converted to hydroxyphenylpyruvate by prephenate dehydrogenase (PD). This work reports the first characterization of the independently expressed PD domain of bifunctional CM-PD from the crenarchaeon Ignicoccus hospitalis and the first functional studies of both full-length CM-PD and the PD domain from the bacterium Haemophilus influenzae. All proteins were hexa-histidine tagged, expressed in Escherichia coli and purified. Expression and purification of I. hospitalis CM-PD generated a degradation product identified as a PD fragment lacking the protein's first 80 residues, Δ80CM-PD. A comparable stable PD domain could also be generated by limited tryptic digestion of this bifunctional enzyme. Thus, Δ80CM-PD constructs were prepared in both organisms. CM-PD and Δ80CM-PD from both organisms were dimeric and displayed the predicted enzymatic activities and thermal stabilities in accord with their hyperthermophilic and mesophilic origins. In contrast with H. influenzae PD activity which was NAD+-specific and displayed >75% inhibition with 50μM l-Tyr, I. hospitalis PD demonstrated dual cofactor specificity with a preference for NADP+ and an insensitivity to l-Tyr. These properties are consistent with a model of the I. hospitalis PD domain based on the previously reported structure of the H. influenzae homolog. Our results highlight the similarities and differences between the archaeal and bacterial TyrA proteins and reveal that the PD activity of both prokaryotes can be successfully mapped to a functionally independent unit. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. A nanotherapy strategy significantly enhances anticryptosporidial activity of an inhibitor of bifunctional thymidylate synthase-dihydrofolate reductase from Cryptosporidium.

    Science.gov (United States)

    Mukerjee, Anindita; Iyidogan, Pinar; Castellanos-Gonzalez, Alejandro; Cisneros, José A; Czyzyk, Daniel; Ranjan, Amalendu Prakash; Jorgensen, William L; White, A Clinton; Vishwanatha, Jamboor K; Anderson, Karen S

    2015-01-01

    Cryptosporidiosis, a gastrointestinal disease caused by protozoans of the genus Cryptosporidium, is a common cause of diarrheal diseases and often fatal in immunocompromised individuals. Bifunctional thymidylate synthase-dihydrofolate reductase (TS-DHFR) from Cryptosporidium hominis (C. hominis) has been a molecular target for inhibitor design. C. hominis TS-DHFR inhibitors with nM potency at a biochemical level have been developed however drug delivery to achieve comparable antiparasitic activity in Cryptosporidium infected cell culture has been a major hurdle for designing effective therapies. Previous mechanistic and structural studies have identified compound 906 as a nM C. hominis TS-DHFR inhibitor in vitro, having μM antiparasitic activity in cell culture. In this work, proof of concept studies are presented using a nanotherapy approach to improve drug delivery and the antiparasitic activity of 906 in cell culture. We utilized PLGA nanoparticles that were loaded with 906 (NP-906) and conjugated with antibodies to the Cryptosporidium specific protein, CP2, on the nanoparticle surface in order to specifically target the parasite. Our results indicate that CP2 labeled NP-906 (CP2-NP-906) reduces the level of parasites by 200-fold in cell culture, while NP-906 resulted in 4.4-fold decrease. Moreover, the anticryptosporidial potency of 906 improved 15 to 78-fold confirming the utility of the antibody conjugated nanoparticles as an effective drug delivery strategy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Cell-Surface Glyco-Engineering by Exogenous Enzymatic Transfer Using a Bifunctional CMP-Neu5Ac Derivative.

    Science.gov (United States)

    Capicciotti, Chantelle J; Zong, Chengli; Sheikh, M Osman; Sun, Tiantian; Wells, Lance; Boons, Geert-Jan

    2017-09-27

    Cell-surface engineering strategies that permit long-lived display of well-defined, functionally active molecules are highly attractive for eliciting desired cellular responses and for understanding biological processes. Current methodologies for the exogenous introduction of synthetic biomolecules often result in short-lived presentations, or require genetic manipulation to facilitate membrane attachment. Herein, we report a cell-surface engineering strategy that is based on the use of a CMP-Neu5Ac derivative that is modified at C-5 by a bifunctional entity composed of a complex synthetic heparan sulfate (HS) oligosaccharide and biotin. It is shown that recombinant ST6GAL1 can readily transfer the modified sialic acid to N-glycans of glycoprotein acceptors of living cells resulting in long-lived display. The HS oligosaccharide is functionally active, can restore protein binding, and allows activation of cell signaling events of HS-deficient cells. The cell-surface engineering methodology can easily be adapted to any cell type and is highly amenable to a wide range of complex biomolecules.

  3. Biochemical characterization of a bifunctional acetaldehyde-alcohol dehydrogenase purified from a facultative anaerobic bacterium Citrobacter sp. S-77.

    Science.gov (United States)

    Tsuji, Kohsei; Yoon, Ki-Seok; Ogo, Seiji

    2016-03-01

    Acetaldehyde-alcohol dehydrogenase (ADHE) is a bifunctional enzyme consisting of two domains of an N-terminal acetaldehyde dehydrogenase (ALDH) and a C-terminal alcohol dehydrogenase (ADH). The enzyme is known to be important in the cellular alcohol metabolism. However, the role of coenzyme A-acylating ADHE responsible for ethanol production from acetyl-CoA remains uncertain. Here, we present the purification and biochemical characterization of an ADHE from Citrobacter sp. S-77 (ADHE(S77)). Interestingly, the ADHE(S77) was unable to be solubilized from membrane with detergents either 1% Triton X-100 or 1% Sulfobetaine 3-12. However, the enzyme was easily dissociated from membrane by high-salt buffers containing either 1.0 M NaCl or (NH(4))(2)SO(4) without detergents. The molecular weight of a native protein was estimated as approximately 400 kDa, consisting of four identical subunits of 96.3 kDa. Based on the specific activity and kinetic analysis, the ADHES77 tended to have catalytic reaction towards acetaldehyde elimination rather than acetaldehyde formation. Our experimental observation suggests that the ADHES77 may play a pivotal role in modulating intracellular acetaldehyde concentration. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  4. Tethering metal ions to photocatalyst particulate surfaces by bifunctional molecular linkers for efficient hydrogen evolution

    KAUST Repository

    Yu, Weili

    2014-08-19

    A simple and versatile method for the preparation of photocatalyst particulates modified with effective cocatalysts is presented; the method involves the sequential soaking of photocatalyst particulates in solutions containing bifunctional organic linkers and metal ions. The modification of the particulate surfaces is a universal and reproducible method because the molecular linkers utilize strong covalent bonds, which in turn result in modified monolayer with a small but controlled quantity of metals. The photocatalysis results indicated that the CdS with likely photochemically reduced Pd and Ni, which were initially immobilized via ethanedithiol (EDT) as a linker, were highly efficient for photocatalytic hydrogen evolution from Na2S-Na2SO3-containing aqueous solutions. The method developed in this study opens a new synthesis route for the preparation of effective photocatalysts with various combinations of bifunctional linkers, metals, and photocatalyst particulate materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. New bifunctional anion-exchange resins for nuclear waste treatment: Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, S.F.; Jarvinen, G.D.; Barr, M.E. [Los Alamos National Lab., NM (United States); Bartsch, R.A. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Chemistry and Biochemistry

    1997-06-01

    Additional bifunctional anion-exchange resins have been designed, synthesized and evaluated for their ability to take up Pu(IV) from nitric acid solutions. Bifunctionality is achieved by adding a second anion-exchange site to the pyridine nitrogen (also an anion-exchange site) of the base poly(4-vinylpyridine) resin. Previous work focused on the effect of varying the chemical properties of the added site along with the length of an alkylene spacer between the two sites. Here the authors examine four new 3- and 4-picolyl derivatives which maintain more rigidly defined geometries between the two nitrogen cationic sites. These materials, which have the two anion-exchange sites separated by three and four carbons, respectively, exhibit lower overall Pu(IV) distribution coefficients than the corresponding N-alkylenepyridium derivatives with more flexible spacers. Methylation of the second pyridium site results in a ca. 20% increase in the Pu(IV) distribution coefficients.

  6. First-Principles Study of Structure Property Relationships of Monolayer (Hydroxy)Oxide-Metal Bifunctional Electrocatalysts

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Kubal, Joseph; Greeley, Jeffrey Philip

    2015-01-01

    under alkaline electrochemical conditions. We demonstrate that the structure and oxidation state of the films can be systematically tuned by changing the applied electrode potential and/or the nature of substrates. Structural features determined from the theoretical calculations provide a wealth...... of information that is inaccessible by purely experimental means, and these structures, in turn, strongly suggest that a bifunctional reaction mechanism for alkaline HER will be operative at the interface between the films, the metal substrates, and the surrounding aqueous medium. This bifunctionality produces...... important changes in the calculated barriers of key elementary reaction steps, including water activation and dissociation, as compared to traditional monofunctional Pt surfaces. The successful identification of the structures of thin metal films and three-phase boundary catalysts is not only an important...

  7. Enhancement of Bacillus thuringiensis insecticidal activity by combining Cry1Ac and bi-functional toxin HWTX-XI from spider.

    Science.gov (United States)

    Sun, Yunjun; Fu, Zujiao; He, Xiaohong; Yuan, Chunhua; Ding, Xuezhi; Xia, Liqiu

    2016-03-01

    In order to assess the potency of bi-functional HWTX-XI toxin from spider Ornithoctonus huwena in improving the insecticidal activity of Bacillus thuringiensis, a fusion gene of cry1Ac and hwtx-XI was constructed and expressed in an acrystalliferous B. thuringiensis strain Cry(-)B. Western blot analysis and microscopic observation revealed that the recombinant strain could express 140-kDa Cry1Ac-HWTX-XI fusion protein and produce parasporal inclusions during sporulation. Bioassay using the larvae of Helicoverpa armigera and Spodoptera exigua showed that the Cry1Ac-HWTX-XI fusion was more toxic than the control Cry1Ac protoxin, as revealed by 95% lethal concentration. Our study indicated that the HWTX-XI from spider might be a candidate for enhancing the toxicity of B. thuringiensis products. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Radiation Induced Crosslinking of Polyethylene in the Presence of Bifunctional Vinyl Monomers

    DEFF Research Database (Denmark)

    Joshi, M. S.; Singer, Klaus Albert Julius; Silverman, J.

    1977-01-01

    Several reports have been published showing that the radiation induced grafting of bifunctional vinyl monomers to low density polyethylene results in a product with an unusually high density of crosslinks. The same grafting reactions are shown to reduce the incipient gel dose by more than a factor...... of fifty. This paper is concerned with the apparent crosslinking produced by the radiation grafting of two monomers to polyethylene: acrylic acid and acrylonitrile....

  9. Bifunctional ligands in combination with phosphines and Lewis acidic phosphonium [corrected] for the carbonylative Sonogashira reaction.

    Science.gov (United States)

    Tan, Chen; Wang, Peng; Liu, Huan; Zhao, Xiao-Li; Lu, Yong; Liu, Ye

    2015-07-11

    The combination of phosphine-ligated Pd catalysis and phosphonium(V) [corrected] Lewis acid catalysis has been developed for the carbonylative Sonogashira reaction using phosphino-phosphonium [corrected] salts (L1-L4) as bifunctional ligands, in which the Lewis acidic phosphonium(V) [corrected] cations can form secondary bonds with O atoms (in C=O) to cooperatively stabilize Pd-acyl intermediates.

  10. 3D Ordered Mesoporous Bifunctional Oxygen Catalyst for Electrically Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Park, Moon Gyu; Lee, Dong Un; Seo, Min Ho; Cano, Zachary Paul; Chen, Zhongwei

    2016-05-01

    To enhance energy efficiency and durability, a highly active and durable 3D ordered mesoporous cobalt oxide framework has been developed for rechargeable zinc-air batteries. The bifunctional air electrode consisting of 3DOM Co3 O4 having high active surface area and robust structure, results in superior charge and discharge battery voltages, and durable performance for electrically rechargeable zinc-air batteries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Development of Novel Bifunctional Compounds That Induce Apoptosis in Prostate Cancer Cells

    Science.gov (United States)

    2009-03-01

    by centrifugation at 1,000 g for 20 minutes at 4jC. The pellet was resuspended in 2 volumes of lysis buffer, to which SDS and sodium chloride were...identified is consistent with the major adduct formed by reaction of bifunctional aniline mustard drugs with DNA (15–18) and is the product of the...dissociation which results in the release of the protonated base. Selected reaction monitoring was preformed for the formation of guanine cations

  12. Bifunctional Perovskite Oxide Catalysts for Oxygen Reduction and Evolution in Alkaline Media.

    Science.gov (United States)

    Gupta, Shiva; Kellogg, William; Xu, Hui; Liu, Xien; Cho, Jaephil; Wu, Gang

    2016-01-01

    Oxygen electrocatalysis, namely of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), governs the performance of numerous electrochemical energy systems such as reversible fuel cells, metal-air batteries, and water electrolyzers. However, the sluggish kinetics of these two reactions and their dependency on expensive noble metal catalysts (e.g, Pt or Ir) prohibit the sustainable commercialization of these highly innovative and in-demand technologies. Bifunctional perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts (NPMC) for oxygen electrocatalysis in alkaline media. In this review, we discuss the state-of-the-art understanding of bifunctional properties of perovskites with regards to their OER/ORR activity in alkaline media and review the associated reaction mechanisms on the oxides surface and the related activity descriptors developed in the recent literature. We also summarize the present strategies to modify their electronic structure and to further improve their performance for the ORR/OER through highlighting the new concepts relating to the role of surface redox chemistry and oxygen deficiency of perovskite oxides for the ORR/OER activity. In addition, we provide a brief account of recently developed advanced perovskite-nanocarbon hybrid bifunctional catalysts with much improved performances. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Mechanical Characterization of a Bi-functional Tetronic Hydrogel Adhesive for Soft Tissues

    Science.gov (United States)

    Sanders, Lindsey; Stone, Roland; Webb, C. Kenneth; Mefford, O. Thompson; Nagatomi, Jiro

    2014-01-01

    Although a number of tissue adhesives and sealants for surgical use are currently available, attaining a useful balance in high strength, high compliance, and low swelling has proven difficult. Recent studies have demonstrated that a 4-arm poly(propylene oxide)-poly(ethylene oxide) (PPO-PEO) block copolymer, Tetronic, can be chemically modified to form a hydrogel tissue adhesive21–23. Building on the success of these studies, the present study explored bi-functionalization of Tetronic with acrylates for chemical crosslinking of the hydrogel and N-hydroxysuccinimide (NHS) for reaction with tissue amines. The adhesive bond strengths of various uni- and bi-functional Tetronic blends (T1107 ACR: T1107 ACR/NHS) determined by lap shear testing ranged between 8 and 74 kPa, with the 75:25 (T1107 ACR: T1107 ACR/NHS) blend displaying the highest value. These results indicated that addition of NHS led to improvement of tissue bond strength over acrylation alone Furthermore, ex vivo pressure tests using the rat bladder demonstrated that the bi-functional Tetronic adhesive exhibited high compliance and maintained pressures under hundreds of filling and emptying cycles. Together, the results of the present study provided evidence that the bi-functional Tetronic adhesive with a proper blend ratio may be used to achieve an accurate balance in bulk and tissue bond strengths, as well as the compliance and durability for soft tissue such as the bladder. PMID:25111445

  14. Collagen/chitosan based two-compartment and bi-functional dermal scaffolds for skin regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feng [Department of Plastic Surgery and Burns, Shenzhen Second People' s Hospital, Shenzhen 518035 (China); Wang, Mingbo [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); She, Zhending [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shenzhen Lando Biomaterials Co., Ltd., Shenzhen 518057 (China); Fan, Kunwu; Xu, Cheng [Department of Plastic Surgery and Burns, Shenzhen Second People' s Hospital, Shenzhen 518035 (China); Chu, Bin; Chen, Changsheng [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shi, Shengjun, E-mail: shengjunshi@yahoo.com [The Burns Department of Zhujiang Hospital, Southern Medical University, Guangzhou 510280 (China); Tan, Rongwei, E-mail: tanrw@landobiom.com [Key Laboratory of Biomedical Materials and Implants, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Shenzhen Lando Biomaterials Co., Ltd., Shenzhen 518057 (China)

    2015-07-01

    Inspired from the sophisticated bilayer structures of natural dermis, here, we reported collagen/chitosan based two-compartment and bi-functional dermal scaffolds. Two functions refer to mediating rapid angiogenesis based on recombinant human vascular endothelial growth factor (rhVEGF) and antibacterial from gentamicin, which were encapsulated in PLGA microspheres. The gentamicin and rhVEGF encapsulated PLGA microspheres were further combined with collagen/chitosan mixtures in low (lower layer) and high (upper layer) concentrations, and molded to generate the two-compartment and bi-functional scaffolds. Based on morphology and pore structure analyses, it was found that the scaffold has a distinct double layered porous and connective structure with PLGA microspheres encapsulated. Statistical analysis indicated that the pores in the upper layer and in the lower layer have great variations in diameter, indicative of a two-compartment structure. The release profiles of gentamicin and rhVEGF exceeded 28 and 49 days, respectively. In vitro culture of mouse fibroblasts showed that the scaffold can facilitate cell adhesion and proliferation. Moreover, the scaffold can obviously inhibit proliferation of Staphylococcus aureus and Serratia marcescens, exhibiting its unique antibacterial effect. The two-compartment and bi-functional dermal scaffolds can be a promising candidate for skin regeneration. - Highlights: • The dermal scaffold is inspired from the bilayer structures of natural dermis. • The dermal scaffold has two-compartment structures. • The dermal scaffold containing VEGF and gentamicin encapsulated PLGA microspheres • The dermal scaffold can facilitate cell adhesion and proliferation.

  15. A New Synthesis of TE2A-a Potential Bifunctional Chelator for {sup 64}Cu

    Energy Technology Data Exchange (ETDEWEB)

    Pandya, Darpan N.; Kwak, Won Jung; Park, Jeong Chan; Gawande, Manoj B.; Yoo, Jeong Soo [Kyungpook National University, Daegu (Korea, Republic of); Kim, Jung Young; An, Gwang Il [Molecular Imaging Research Center, Seoul (Korea, Republic of); Ryu, Eun Kyoung [Korea Basic Science Institute, Chungbuk (Korea, Republic of)

    2010-09-15

    The development of a new bifunctional chelator, which holds radio metals strongly in living systems, is a prerequisite for the successful application of disease-specific biomolecules to medical diagnosis and therapy. Recently, TE2A was reported to make kinetically more stable Cu({Pi}) complexes than TETA. Herein, we report a new synthetic route to TE2A and explore its potential as a bifunctional chelator. TE2A was synthesized using the regioselective alkylation of benzyl bromoacetate and successive de protection of the methylene bridge and benzyl group. Salt-free TE2A was radiolabeled with {sup 64}Cu and micro PET imaging was performed to follow the clearance pattern of the {sup 64}Cu-TE2A complex. TE2A was conjugated with cyclic RGD peptide and the TE2A-c(RGDyK) conjugate was radiolabeled with {sup 64}Cu. TE2A was prepared in salt-free form cyclam in an overall yield of 74%. The micro PET images showed that {sup 64}Cu-TE2A is excreted rapidly from the body by the kidney and liver. TE2A was successfully conjugated with c(RGDyK) peptide through on carboxylate group and the TE2A-c(RGDyK) conjugate was radiolabeled with {sup 64}Cu in 94% yield within 30 min. TE2A can be used by itself as a bifunctional chelator without any further structural modification.

  16. Bifunctional bridging linker-assisted synthesis and characterization of TiO{sub 2}/Au nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Žunič, Vojka, E-mail: vojka.zunic@ijs.si, E-mail: vojka13@gmail.com; Kurtjak, Mario; Suvorov, Danilo [Jožef Stefan Institute, Advanced Materials Department (Slovenia)

    2016-11-15

    Using a simple organic bifunctional bridging linker, titanium dioxide (TiO{sub 2}) nanoparticles were coupled with the Au nanoparticles to form TiO{sub 2}/Au nanocomposites with a variety of Au loadings. This organic bifunctional linker, meso-2,3-dimercaptosuccinic acid, contains two types of functional groups: (i) the carboxyl group, which enables binding to the TiO{sub 2}, and (ii) the thiol group, which enables binding to the Au. In addition, the organic bifunctional linker acts as a stabilizing agent to prevent the agglomeration and growth of the Au particles, resulting in the formation of highly dispersed Au nanoparticles. To form the TiO{sub 2}/Au nanocomposites in a simple way, we deliberately applied a synthetic method that simultaneously ensures: (i) the capping of the Au nanoparticles and (ii) the binding of different amounts of Au to the TiO{sub 2}. The TiO{sub 2}/Au nanocomposites formed with this method show enhanced UV and Vis photocatalytic activities when compared to the pure TiO{sub 2} nanopowders.Graphical Abstract.

  17. Development of Cobalt Hydroxide as a Bifunctional Catalyst for Oxygen Electrocatalysis in Alkaline Solution.

    Science.gov (United States)

    Zhan, Yi; Du, Guojun; Yang, Shiliu; Xu, Chaohe; Lu, Meihua; Liu, Zhaolin; Lee, Jim Yang

    2015-06-17

    Co(OH)2 in the form of hexagonal nanoplates synthesized by a simple hydrothermal reaction has shown even greater activity than cobalt oxides (CoO and Co3O4) in oxygen reduction and oxygen evolution reactions (ORR and OER) under alkaline conditions. The bifunctionality for oxygen electrocatalysis as shown by the OER-ORR potential difference (ΔE) could be reduced to as low as 0.87 V, comparable to the state-of-the-art non-noble bifunctional catalysts, when the Co(OH)2 nanoplates were compounded with nitrogen-doped reduced graphene oxide (N-rGO). The good performance was attributed to the nanosizing of Co(OH)2 and the synergistic interaction between Co(OH)2 and N-rGO. A zinc-air cell assembled with a Co(OH)2-air electrode also showed a performance comparable to that of the state-of-the-art zinc-air cells. The combination of bifunctional activity and operational stability establishes Co(OH)2 as an effective low-cost alternative to the platinum group metal catalysts.

  18. Bifunctional Transition Metal Hydroxysulfides: Room-Temperature Sulfurization and Their Applications in Zn-Air Batteries.

    Science.gov (United States)

    Wang, Hao-Fan; Tang, Cheng; Wang, Bin; Li, Bo-Quan; Zhang, Qiang

    2017-09-01

    Bifunctional electrocatalysis for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) constitutes the bottleneck of various sustainable energy devices and systems like rechargeable metal-air batteries. Emerging catalyst materials are strongly requested toward superior electrocatalytic activities and practical applications. In this study, transition metal hydroxysulfides are presented as bifunctional OER/ORR electrocatalysts for Zn-air batteries. By simply immersing Co-based hydroxide precursor into solution with high-concentration S(2-) , transition metal hydroxides convert to hydroxysulfides with excellent morphology preservation at room temperature. The as-obtained Co-based metal hydroxysulfides are with high intrinsic reactivity and electrical conductivity. The electron structure of the active sites is adjusted by anion modulation. The potential for 10 mA cm(-2) OER current density is 1.588 V versus reversible hydrogen electrode (RHE), and the ORR half-wave potential is 0.721 V versus RHE, with a potential gap of 0.867 V for bifunctional oxygen electrocatalysis. The Co3 FeS1.5 (OH)6 hydroxysulfides are employed in the air electrode for a rechargeable Zn-air battery with a small overpotential of 0.86 V at 20.0 mA cm(-2) , a high specific capacity of 898 mAh g(-1) , and a long cycling life, which is much better than Pt and Ir-based electrocatalyst in Zn-air batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Thrombomodulin: A Bifunctional Modulator of Inflammation and Coagulation in Sepsis

    Directory of Open Access Journals (Sweden)

    Takayuki Okamoto

    2012-01-01

    Full Text Available Deregulated interplay between inflammation and coagulation plays a pivotal role in the pathogenesis of sepsis. Therapeutic approaches that simultaneously target both inflammation and coagulation hold great promise for the treatment of sepsis. Thrombomodulin is an endogenous anticoagulant protein that, in cooperation with protein C and thrombin-activatable fibrinolysis inhibitor, serves to maintain the endothelial microenvironment in an anti-inflammatory and anticoagulant state. A recombinant soluble form of thrombomodulin has been approved to treat patients suffering from disseminated intravascular coagulation (DIC and has thus far shown greater therapeutic potential than heparin. A phase II clinical trial is currently underway in the USA to study the efficacy of thrombomodulin for the treatment of sepsis with DIC complications. This paper focuses on the critical roles that thrombomodulin plays at the intersection of inflammation and coagulation and proposes the possible existence of interactions with integrins via protein C. Finally, we provide a rationale for the clinical application of thrombomodulin for alleviating sepsis.

  20. Cloning, functional expression and characterization of a bifunctional 3-hydroxybutanal dehydrogenase /reductase involved in acetone metabolism by Desulfococcus biacutus.

    Science.gov (United States)

    Frey, Jasmin; Rusche, Hendrik; Schink, Bernhard; Schleheck, David

    2016-11-25

    The strictly anaerobic, sulfate-reducing bacterium Desulfococcus biacutus can utilize acetone as sole carbon and energy source for growth. Whereas in aerobic and nitrate-reducing bacteria acetone is activated by carboxylation with CO 2 to acetoacetate, D. biacutus involves CO as a cosubstrate for acetone activation through a different, so far unknown pathway. Proteomic studies indicated that, among others, a predicted medium-chain dehydrogenase/reductase (MDR) superfamily, zinc-dependent alcohol dehydrogenase (locus tag DebiaDRAFT_04514) is specifically and highly produced during growth with acetone. The MDR gene DebiaDRAFT_04514 was cloned and overexpressed in E. coli. The purified recombinant protein required zinc as cofactor, and accepted NADH/NAD + but not NADPH/NADP + as electron donor/acceptor. The pH optimum was at pH 8, and the temperature optimum at 45 °C. Highest specific activities were observed for reduction of C 3 - C 5 -aldehydes with NADH, such as propanal to propanol (380 ± 15 mU mg -1 protein), butanal to butanol (300 ± 24 mU mg -1 ), and 3-hydroxybutanal to 1,3-butanediol (248 ± 60 mU mg -1 ), however, the enzyme also oxidized 3-hydroxybutanal with NAD + to acetoacetaldehyde (83 ± 18 mU mg -1 ). The enzyme might play a key role in acetone degradation by D. biacutus, for example as a bifunctional 3-hydroxybutanal dehydrogenase/reductase. Its recombinant production may represent an important step in the elucidation of the complete degradation pathway.

  1. Nanostructured Perovskite LaCo1-xMnxO3 as Bifunctional Catalysts for Rechargeable Metal-Air Batteries

    Science.gov (United States)

    Ge, Xiaoming; Li, Bing; Wuu, Delvin; Sumboja, Afriyanti; An, Tao; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

    2015-09-01

    Bifunctional catalyst that is active for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the most important components of rechargeable metal-air batteries. Nanostructured perovskite bifunctional catalysts comprising La, Co and Mn(LaCo1-xMnxO3, LCMO) are synthesized by hydrothermal methods. The morphology, structure and electrochemical activity of the perovskite bifunctional catalysts are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and rotating disk electrode (RDE) techniques. Nanorod, nanodisc and nanoparticle are typical morphologies of LCMO. The electrocatalytic activity of LCMO is significantly improved by the addition of conductive materials such as carbon nanotube. To demonstrate the practical utilization, LCMO in the composition of LaCo0.8Mn0.2O3(LCMO82) is used as air cathode catalysts for rechargeable zinc-air batteries. The battery prototype can sustain 470 h or 40 discharge-charge cycles equivalent.

  2. Bifunctional activity of deoxyhypusine synthase/hydroxylase from Trichomonas vaginalis.

    Science.gov (United States)

    Quintas-Granados, Laura Itzel; Carvajal Gamez, Bertha Isabel; Villalpando, Jose Luis; Ortega-Lopez, Jaime; Arroyo, Rossana; Azuara-Liceaga, Elisa; Álvarez-Sánchez, María Elizbeth

    2016-04-01

    The Trichomonas vaginalis genome analysis suggested the presence of a putative deoxyhypusine synthase (TvDHS) that catalyzes the posttranslational modification of eIF-5A. Herein, we expressed and purified the recombinant TvDHS (rTvDHS) protein (43 kDa) and the recombinant TveIF-5A (rTveIF-5A) precursor protein (46 kDa). A 41 kDa band of the native TvDHS was recognized by western blot analysis in T. vaginalis total protein extract by a mouse polyclonal anti-rTvDHS antibody. The enzymatic activity of rTvDHS was determined by in vitro rTveIF-5A precursor modification. The modification reaction was performed by using ((3)H)-spermidine, and the biochemical analysis showed that rTvDHS exhibited Km value of 0.6 μM. The rTvDHS activity was inhibited by the spermidine analog, N″-guanyl-1,7-diamino-heptane (GC7). Native gel electrophoresis analysis showed two bands corresponding to an rTvDHS-rTveIF-5A complex and an intermediate form of rTveIF-5A. The two forms were subsequently separated by ion exchange chromatography to identify the hypusine residue by MS/MS analysis. Moreover, mutations in TvDHS showed that the putative HE motif present in this enzyme is involved in the hydroxylation of TveIF-5A. We observed that only hypusine-containing TveIF-5A was bound to an RNA hairpin ERE structure from the cox-2 gene, which contains the AAAUGUCACAC consensus sequence. Interestingly, 2DE-WB assays, using parasites that were grown in DAB-culture conditions and transferred to exogenous putrescine, showed the new isoform of TveIF-5A. In summary, our results indicate that T. vaginalis contains an active TvDHS capable of modifying the precursor TveIF-5A protein, which subsequently exhibits RNA binding activity. Copyright © 2015. Published by Elsevier B.V.

  3. Mechanical characterization of a bifunctional Tetronic hydrogel adhesive for soft tissues.

    Science.gov (United States)

    Sanders, Lindsey; Stone, Roland; Webb, Kenneth; Mefford, Thompson; Nagatomi, Jiro

    2015-03-01

    Although a number of tissue adhesives and sealants for surgical use are currently available, attaining a useful balance in high strength, high compliance, and low swelling has proven difficult. Recent studies have demonstrated that a four-arm poly(propylene oxide)-poly(ethylene oxide) block copolymer, Tetronic, can be chemically modified to form a hydrogel tissue adhesive (Cho et al., Acta Biomater 2012;8:2223-2232; Barrett et al., Adv Health Mater 2012;1-11; Balakrishnan, Evaluating mechanical performance of hydrogel-based adhesives for soft tissue applications. Clemson University, All Theses, Paper 1574: Tiger Prints; 2013). Building on the success of these studies, this study explored bifunctionalization of Tetronic with acrylates for chemical crosslinking of the hydrogel and N-hydroxysuccinimide (NHS) for reaction with tissue amines. The adhesive bond strengths of various uni and bifunctional Tetronic blends (T1107 ACR: T1107 ACR/NHS) determined by lap shear testing ranged between 8 and 74 kPa, with the 75:25 (T1107 ACR: T1107 ACR/NHS) blend displaying the highest value. These results indicated that addition of NHS led to improvement of tissue bond strength over acrylation alone. Furthermore, ex vivo pressure tests using the rat bladder demonstrated that the bifunctional Tetronic adhesive exhibited high compliance and maintained pressures under hundreds of filling and emptying cycles. Together, the results of this study provided evidence that the bifunctional Tetronic adhesive with a proper blend ratio may be used to achieve an accurate balance in bulk and tissue bond strengths, as well as the compliance and durability for soft tissue such as the bladder. © 2014 Wiley Periodicals, Inc.

  4. Bifunctional heterogeneous catalysts from oil palm empty fruit bunches ash and alum for biodiesel synthesis simultaneously

    Science.gov (United States)

    Astar, Ismail; Usman, Thamrin; Wahyuni, Nelly; Rudiyansyah, Alimuddin, Andi Hairil

    2017-03-01

    Free fatty acids (FFA) contained in crude palm oil (CPO) and sludge oil has been used as the base material of biodiesel with the aid of a catalyst in the transesterification and esterification reactions. This study aims to synthesize and characterize bifunctional catalysts were synthesized from the ashes of palm empty fruit bunches (EFB) and alum based on the analysis of XRD, XRF and acidity test. Bifunctional catalyst obtained was used as a catalyst to production of biodiesel with different levels of FFA. The optimum ratio alum added was 0.2 mol at 3 hours of reaction time and 3% of catalyst by the FFA samples were used 67,40%. The catalyst with optimum alum mole variations subsequently used on samples with varying levels of FFA, namely 1.29%, 4.98%, 29.21%, 67.40% and 74.47%. Optimum conversion of methyl ester in the esterification reaction occurs in the sample with 67.40% FFA content, which reached 86.17%, while the conversion of methyl ester transesterification process optimum amounted to 45.70% in the samples with 4.98% FFA content. Methyl ester produced has a refractive index of 1.448 (29.8 ° C), density of 0.883 g / mL (25 °C) and a viscosity of 8.933 cSt (25 ° C). The results of GC-MS analysis showed that the main composition of methyl ester result of esterification of sludge oil methyl palmitate (36.84%), while the CPO transesterification shows the main composition of methyl ester is methyl oleic (38.87%). Based on the research results, the catalyst synthesized from alum and EFB ash can be used as a Bifunctional catalysts for biodiesel synthesis.

  5. Induction of Axial Chirality in 8-Arylquinolines through Halogenation Reactions Using Bifunctional Organocatalysts.

    Science.gov (United States)

    Miyaji, Ryota; Asano, Keisuke; Matsubara, Seijiro

    2017-07-26

    The enantioselective syntheses of axially chiral heterobiaryls were accomplished through the aromatic electrophilic halogenation of 3-(quinolin-8-yl)phenols with bifunctional organocatalysts that control the molecular conformations during successive halogenations. Axially chiral quinoline derivatives, which have rarely been synthesized in an enantioselective catalytic manner, were afforded in moderate-to-good enantioselectivities through bromination, and an analogous protocol also enabled enantioselective iodination. In addition, this catalytic reaction, which allows enantioselective control through the use of mono-ortho-substituted substrates, allowed the asymmetric synthesis of 8-arylquinoline derivatives bearing two different halogen groups in high enantioselectivities. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  7. Trypanosoma brucei DHFR-TS Revisited: Characterisation of a Bifunctional and Highly Unstable Recombinant Dihydrofolate Reductase-Thymidylate Synthase.

    Directory of Open Access Journals (Sweden)

    Marc W Gibson

    2016-05-01

    Full Text Available Bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS is a chemically and genetically validated target in African trypanosomes, causative agents of sleeping sickness in humans and nagana in cattle. Here we report the kinetic properties and sensitivity of recombinant enzyme to a range of lipophilic and classical antifolate drugs. The purified recombinant enzyme, expressed as a fusion protein with elongation factor Ts (Tsf in ThyA- Escherichia coli, retains DHFR activity, but lacks any TS activity. TS activity was found to be extremely unstable (half-life of 28 s following desalting of clarified bacterial lysates to remove small molecules. Stability could be improved 700-fold by inclusion of dUMP, but not by other pyrimidine or purine (deoxy-nucleosides or nucleotides. Inclusion of dUMP during purification proved insufficient to prevent inactivation during the purification procedure. Methotrexate and trimetrexate were the most potent inhibitors of DHFR (Ki 0.1 and 0.6 nM, respectively and FdUMP and nolatrexed of TS (Ki 14 and 39 nM, respectively. All inhibitors showed a marked drop-off in potency of 100- to 1,000-fold against trypanosomes grown in low folate medium lacking thymidine. The most potent inhibitors possessed a terminal glutamate moiety suggesting that transport or subsequent retention by polyglutamylation was important for biological activity. Supplementation of culture medium with folate markedly antagonised the potency of these folate-like inhibitors, as did thymidine in the case of the TS inhibitors raltitrexed and pemetrexed.

  8. Trypanosoma brucei DHFR-TS Revisited: Characterisation of a Bifunctional and Highly Unstable Recombinant Dihydrofolate Reductase-Thymidylate Synthase.

    Science.gov (United States)

    Gibson, Marc W; Dewar, Simon; Ong, Han B; Sienkiewicz, Natasha; Fairlamb, Alan H

    2016-05-01

    Bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) is a chemically and genetically validated target in African trypanosomes, causative agents of sleeping sickness in humans and nagana in cattle. Here we report the kinetic properties and sensitivity of recombinant enzyme to a range of lipophilic and classical antifolate drugs. The purified recombinant enzyme, expressed as a fusion protein with elongation factor Ts (Tsf) in ThyA- Escherichia coli, retains DHFR activity, but lacks any TS activity. TS activity was found to be extremely unstable (half-life of 28 s) following desalting of clarified bacterial lysates to remove small molecules. Stability could be improved 700-fold by inclusion of dUMP, but not by other pyrimidine or purine (deoxy)-nucleosides or nucleotides. Inclusion of dUMP during purification proved insufficient to prevent inactivation during the purification procedure. Methotrexate and trimetrexate were the most potent inhibitors of DHFR (Ki 0.1 and 0.6 nM, respectively) and FdUMP and nolatrexed of TS (Ki 14 and 39 nM, respectively). All inhibitors showed a marked drop-off in potency of 100- to 1,000-fold against trypanosomes grown in low folate medium lacking thymidine. The most potent inhibitors possessed a terminal glutamate moiety suggesting that transport or subsequent retention by polyglutamylation was important for biological activity. Supplementation of culture medium with folate markedly antagonised the potency of these folate-like inhibitors, as did thymidine in the case of the TS inhibitors raltitrexed and pemetrexed.

  9. A Bifunctional Geranyl and Geranylgeranyl Diphosphate Synthase Is Involved in Terpene Oleoresin Formation in Picea abies1[W][OA

    Science.gov (United States)

    Schmidt, Axel; Wächtler, Betty; Temp, Ulrike; Krekling, Trygve; Séguin, Armand; Gershenzon, Jonathan

    2010-01-01

    The conifer Picea abies (Norway spruce) defends itself against herbivores and pathogens with a terpenoid-based oleoresin composed chiefly of monoterpenes (C10) and diterpenes (C20). An important group of enzymes in oleoresin biosynthesis are the short-chain isoprenyl diphosphate synthases that produce geranyl diphosphate (C10), farnesyl diphosphate (C15), and geranylgeranyl diphosphate (C20) as precursors of different terpenoid classes. We isolated a gene from P. abies via a homology-based polymerase chain reaction approach that encodes a short-chain isoprenyl diphosphate synthase making an unusual mixture of two products, geranyl diphosphate (C10) and geranylgeranyl diphosphate (C20). This bifunctionality was confirmed by expression in both prokaryotic (Escherichia coli) and eukaryotic (P. abies embryogenic tissue) hosts. Thus, this isoprenyl diphosphate synthase, designated PaIDS1, could contribute to the biosynthesis of both major terpene types in P. abies oleoresin. In saplings, PaIDS1 transcript was restricted to wood and bark, and transcript level increased dramatically after methyl jasmonate treatment, which induces the formation of new (traumatic) resin ducts. Polyclonal antibodies localized the PaIDS1 protein to the epithelial cells surrounding the traumatic resin ducts. PaIDS1 has a close phylogenetic relationship to single-product conifer geranyl diphosphate and geranylgeranyl diphosphate synthases. Its catalytic properties and reaction mechanism resemble those of conifer geranylgeranyl diphosphate synthases, except that significant quantities of the intermediate geranyl diphosphate are released. Using site-directed mutagenesis and chimeras of PaIDS1 with single-product geranyl diphosphate and geranylgeranyl diphosphate synthases, specific amino acid residues were identified that alter the relative composition of geranyl to geranylgeranyl diphosphate. PMID:19939949

  10. Bifunctional metal-free catalysis of mesoporous noble carbons for oxygen reduction and evolution reactions.

    Science.gov (United States)

    Sakaushi, Ken; Fellinger, Tim-Patrick; Antonietti, Markus

    2015-04-13

    Electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key reactions in lithium-oxygen batteries (LOBs) being a promising candidate to store renewable energies due to their high specific energy. However current development on LOBs is suffering from unsuitable catalysts. In particular, carbon-based catalysts were found to perform poorly in this system. Here, we show that metal-free mesoporous nitrogen-doped carbons (meso-NdCs) offer highly promising performances in both ORR and OER; they act as bifunctional catalysts, and can be synthesized by a very simple method. The efficient electrocatalytic activity of ORR and OER was used in a LOB cell during discharge and charge, respectively, and the present system showed a lower overpotential comparable to metal-based catalysts in LOB system. Thus, we demonstrate that meso-NdCs act as a new and affordable candidate for the efficient bifunctional oxygen catalysis, therefore can be applied to many energy-related applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Orderly Layered Zr-Benzylphosphonate Nanohybrids for Efficient Acid-Base-Mediated Bifunctional/Cascade Catalysis.

    Science.gov (United States)

    Li, Hu; Fang, Zhen; He, Jian; Yang, Song

    2017-02-22

    The development of functional metal-organic materials that are robust and active for bifunctional/cascade catalysis is of great significance. Herein, a series of mesoporous and orderly layered nanohybrids were synthesized for the first time through simple and template-free assembly of ortho-, meta-, or para-xylylenediphosphonates (o-, p-, or m-PhP) containing zirconium. It was found that m-PhPZr nanoparticles (20-50 nm) with mesopores centered at 7.9 nm and high Lewis acid-base site ratio (1:0.7) showed excellent performance under mild conditions (as low as 82 °C) in transfer hydrogenation of carbonyl compounds, including bioaldehydes and alcohols, with near quantitative yields and little Zr leaching. Isotopic labeling studies indicated the occurrence of direct hydrogen transfer rather than metal hydride route by bifunctional catalysis. Lewis acidic (Zr) and basic (PO 3 ) centers of the heterogeneous catalyst were further revealed to play a synergistic role in one-pot cascade transformations, for example, of ethyl levulinate to γ-valerolactone and glucose to 5-hydroxymethylfurfural. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Porous NiFe-Oxide Nanocubes as Bifunctional Electrocatalysts for Efficient Water-Splitting.

    Science.gov (United States)

    Kumar, Ashwani; Bhattacharyya, Sayan

    2017-12-06

    Electrocatalytic water-splitting, a combination of oxygen and hydrogen evolution reactions (OER and HER), is highly attractive in clean energy technologies, especially for high-purity hydrogen production, whereas developing stable, earth-abundant, bifunctional catalysts has continued to pose major challenges. Herein, a mesoporous NiFe-oxide nanocube (NiFe-NC) system is developed from a NiFe Prussian blue analog metal-organic framework as an efficient bifunctional catalyst for overall water-splitting. The NiFe-NCs with ∼200 nm side length have a Ni/Fe molar ratio of 3:2 and is a composite of NiO and α/γ-Fe 2 O 3 . The NCs demonstrate overpotentials of 271 and 197 mV for OER and HER, respectively, in 1 M KOH at 10 mA cm -2 , which outperform those of 339 and 347 mV for the spherical NiFe-oxide nanoparticles having a similar composition. The electrolyzer constructed using NiFe-NCs requires an impressive cell voltage of 1.67 V to deliver a current density of 10 mA cm -2 . Along with a mesoporous structure with a broad pore size distribution, the NiFe-NCs demonstrate the qualities of a desired corrosion-resistant water-splitting catalyst with long-term stability. The exposure of active sites at the edges and vertices of the NCs was validated to play a crucial role in their overall catalytic performance.

  13. Strongly Coupled Molybdenum Carbide on Carbon Sheets as a Bifunctional Electrocatalyst for Overall Water Splitting.

    Science.gov (United States)

    Wang, Hao; Cao, Yingjie; Sun, Cheng; Zou, Guifu; Huang, Jianwen; Kuai, Xiaoxiao; Zhao, Jianqing; Gao, Lijun

    2017-09-22

    High-performance and affordable electrocatalysts from earth-abundant elements are desirably pursued for water splitting involving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Here, a bifunctional electrocatalyst of highly crystalline Mo 2 C nanoparticles supported on carbon sheets (Mo 2 C/CS) was designed toward overall water splitting. Owing to the highly active catalytic nature of Mo 2 C nanoparticles, the high surface area of carbon sheets and efficient charge transfer in the strongly coupled composite, the designed catalysts show excellent bifunctional behavior with an onset potential of -60 mV for HER and an overpotential of 320 mV to achieve a current density of 10 mA cm -2 for OER in 1 m KOH while maintaining robust stability. Moreover, the electrolysis cell using the catalyst only requires a low cell voltage of 1.73 V to achieve a current density of 10 mA cm -2 and maintains the activity for more than 100 h when employing the Mo 2 C/CS catalyst as both anode and cathode electrodes. Such high performance makes Mo 2 C/CS a promising electrocatalyst for practical hydrogen production from water splitting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Magnetically labelled gold and epoxy bi-functional microcarriers for suspension based bioassay technologies.

    Science.gov (United States)

    Vyas, Kunal N; Palfreyman, Justin J; Love, David M; Mitrelias, Thanos; Barnes, Crispin H W

    2012-12-21

    Microarrays and suspension-based assay technologies have attracted significant interest over the past decade with applications ranging from medical diagnostics to high throughput molecular biology. The throughput and sensitivity of a microarray will always be limited by the array density and slow reaction kinetics. Suspension (or bead) based technologies offer a conceptually different approach, improving detection by substituting a fixed plane of operation with many individually distinguishable microcarriers. In addition to all the features of a suspension based assay technology, our technology offers a rewritable label. This has the potential to be truly revolutionary by opening up the possibility of generating, on chip, extensive labelled molecular libraries. We unveil our latest SU-8 microcarrier design with embedded magnetic films that can be utilized for both magnetic and optical labelling. The novel design significantly simplifies fabrication and additionally incorporates a gold cap to provide a dual surface, bi-functional architecture. The microcarriers are fabricated using deep-ultraviolet lithography techniques and metallic thin film growth by evaporation. The bi-functional properties of the microcarriers will allow us to use each microcarrier as its own positive control thereby increasing the reliability of our technology. Here we present details of the design, fabrication, magnetic detection and functionalization of these microcarriers.

  15. Bifunctional silica nanospheres with 3-aminopropyl and phenyl groups. Synthesis approach and prospects of their applications

    Science.gov (United States)

    Kotsyuda, Sofiya S.; Tomina, Veronika V.; Zub, Yuriy L.; Furtat, Iryna M.; Lebed, Anastasia P.; Vaclavikova, Miroslava; Melnyk, Inna V.

    2017-10-01

    Spherical silica particles with bifunctional (tbnd Si(CH2)3NH2/tbnd SiC6H5) surface layers were synthesized by the Stöber method using ternary alkoxysilanes systems. The influence of the synthesis conditions, such as temperature and stirring time on the process of nanoparticles formation was studied. The presence of introduced functional groups was confirmed by FTIR. The composition of the surface layers examined by elemental analysis and acid-base titration was shown to be independent from the synthesis temperature. However, the size of the obtained particles depends on the synthesis temperature and, according to photon cross-correlation spectroscopy, can be varied from 50 to 846 nm. The variation of electric charges of N-functional groups was disclosed in obtained nanospheres and attributed to different surface location of these groups and their surrounding with other groups. The sorption of Cu(II) ions by functionalized silicas depends on the concentration of amino groups, which correlates with the isoelectric point values (determined to vary from 8.26 to 9.21). Bifunctional nanoparticles adsorb 99.0 mg/g of methylene blue, compared with 48.0 mg/g by silica sample with only amino groups. The nanospheres, both with and without adsorbed Cu2+, demonstrate reasonable antibacterial activity against S. aureus ATCC 25923, depending on particle concentration in water suspension.

  16. The development and application of bi-functional clay inhibitor of CYY-2

    Science.gov (United States)

    Li, Yongbin; Li, Fengqun; Yu, Jiliang; Han, Changsheng; Gong, Hui; Wang, Jing; Wu, Yingde; Wang, Rui

    2017-04-01

    with the constant discovery and gradual development of low-permeability and water-sensitivity formation, reservoir protection is especially important for improving water-injection development efficiency and enhancing working level of low-permeability reservoir, which will be a critical sector in enhancing development quality of low-permeability and water-sensitivity reservoir. Combined with the understanding of clay mineral expansion theory, starting from hydratability, polarity and oxidability of adopted materials, one type of bi-functional clay inhibitor, CYY-2, is developed which has the function of swelling prevention and swelling shrinkage, and property evaluation is carried out by adopting different methods and measures. Test results indicated that: by using this bi-functional clay inhibitor, the swelling prevention rate of magcogel and natural core powder could reach to 91.7% and 89.8%, swelling shrinkage of which could reach to 61.3% and 81.5%; in the natural flowing experiment, core damage ratio was declined from 86.3% to 12.8%, and the core permeability could be raised by 3 times averagely; in the field experiment of 5 wells, effective rate of 80%, the well effect, is reached. With the extension of injection time of injecting wells, injection pressure rose constantly, injection allocation request was not finished, which influenced the overall reservoir development effect. So reservoir protection is important to deal with the above problems.

  17. Bifunctional composite microspheres of silica/lanthanide-polyoxometalates/Au: Study on luminescence and catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun, E-mail: junwang924@mail.ccnu.edu.cn; Fan, Shaohua; Zhao, Weiqian; Lu, Xuelian; Li, Wuke

    2013-12-02

    In this paper, the synthesis and properties of composite silica microspheres grafted with gold nanoparticles and lanthanide-polyoxometalates are described. This synthesis employs polyethyleneimine as the crosslink polymer to immobilize the Au nanoparticles and lanthanide-polyoxometalates on silica spheres, which results in the formation of bifunctional composite microspheres of silica/lanthanide-polyoxometalates/Au. The composite material was found to be catalytically active in the oxidation of styrene, and benzaldehyde and styrene oxide were the main products. Catalyzed oxidation of styrene demonstrates the size-dependent activity of catalysts and the smaller catalyst shows the higher selectivity. Moreover, the composite particles show bright red luminescence under UV light, which could be seen by naked eyes. The luminescence properties of composite material and the effect of Au nanoparticles on the luminescence of Eu ion were investigated, and energy could be more effectively transferred from ligand to lanthanide ion when Au nanoparticles were grafted on silica spheres. The integration of luminescent components and Au particles makes it possible to label catalyst and monitor the catalyzed reactions. - Highlights: • The bifunctional composite microspheres were fabricated. • Both polyoxometalates and Au nanoparticles could be grafted on silica spheres. • The composite particles exhibit the excellent luminescence and catalytic activity. • The Au nanoparticles affect the luminescence properties of Eu{sup 3+} ions.

  18. Understanding the molecular mechanism of substrate channeling and domain communication in protozoal bifunctional TS-DHFR.

    Science.gov (United States)

    Anderson, Karen S

    2017-03-01

    Most species, such as humans, have monofunctional forms of thymidylate synthase (TS) and dihydrofolate reductase (DHFR) that are key folate metabolism enzymes making critical folate components required for DNA synthesis. In contrast, several parasitic protozoa, including Leishmania major (Lm), Plasmodium falciparum (Pf), Toxoplasma gondii (Tg) and Cryptosporidium hominis (Ch), contain a unique bifunctional thymidylate synthase-dihydrofolate reductase (TS-DHFR) having the two sequential catalytic activities contained on a single polypeptide chain. It has been suggested that the bifunctional nature of the two catalytic activities may enable substrate channeling. The 3D structures for each of these enzymes reveals distinct features for each species. While three of the four species (Pf, Tg and Ch) contain a junctional region linking the two domains, this is lacking in Lm. The Lm and Pf contain N-terminal amino acid extensions. A multidisciplinary approach using structural studies and transient kinetic analyses combined with mutational analysis has investigated the roles of these unique structural features for each enzyme. Additionally, the possibility of substrate channeling behavior was explored. These studies have identified unique, functional regions in both the TS and DHFR domains that govern efficient catalysis for each species. Surprisingly, even though there are structural similarities among the species, each is regulated in a distinct manner. This structural and mechanistic information was also used to exploit species-specific inhibitor design. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  19. Unprecedented Activity of Bifunctional Electrocatalyst for High Power Density Aqueous Zinc-Air Batteries.

    Science.gov (United States)

    Wang, Mengfan; Qian, Tao; Liu, Sisi; Zhou, Jinqiu; Yan, Chenglin

    2017-06-28

    The development of nonprecious metal catalysts with desirable bifunctional activities to supersede noble metal catalysts is of vital importance for high performance aqueous zinc-air batteries. Here, an unprecedented activity of bifunctional electrocatalyst is reported by in situ growth of nitrogen-enriched carbon nanotubes with transition metal composite. The resultant catalyst delivers surprisingly high OER (potential@10 mA cm -2 of 1.58 V) and ORR (onset potential of 0.97 V, half-wave potential of 0.86 V) performance. The overall oxygen electrode activity (overvoltage between ORR and OER) of the catalyst is as low as 0.72 V. In aqueous Zn-air battery tests, primary batteries demonstrate high maximum power density and two-electrode rechargeable batteries also exhibit good cycle performance. The unprecedented electrocatalyst opens up new avenues for developing highly active nitrogen-doped carbon nanotube-supported electrocatalysts and offers prospects for the next generation of fuel cells, metal-air batteries, and photocatalysis applications.

  20. Synthesis and characterization of ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres

    Science.gov (United States)

    Koc, Kenan; Karakus, Baris; Rajar, Kausar; Alveroglu, Esra

    2017-10-01

    Herein, we synthesized and characterized fluorescent and super paramagnetic ZnS@Fe3O4 nanospheres. First, (3-mercaptopropyl) trimethoxysilane (MPS) capped ZnS quantum dots (QDs) and SiO2 coated Fe3O4 nanoparticles were synthesized separately by using solution growth and co-precipitation techniques. After synthesis and characterization of these two nanoparticles, they were conglutinated together in a nano sized sphere. The QDs were attached to the surface of the Fe3O4 nanoparticles by Sisbnd Osbnd Si bonds and so Sisbnd Osbnd Si bonds created a SiO2 network around the nanoparticles during the formation of the ZnS@Fe3O4 nanospheres. The synthesized MPS capped ZnS fluorescent QDs, SiO2 coated magnetite super paramagnetic nanoparticles and ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres were characterized by using UV-Vis Absorption Spectroscopy, Fluorescence Spectroscopy, X-ray analysis, Vibrating Sample Magnetometer analysis, Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope and Energy-dispersive X-ray spectroscopy. ZnS@Fe3O4 bifunctional nanospheres were shown to retain the magnetic properties of magnetite, while exhibiting the luminescent optical properties of ZnS nanoparticles. The combination of fluorescent and magnetic behaviors of nano composites make them useful for potential applications in the field of bio-medical and environmental.

  1. BACTERIAL BIOFILM FORMATION VERSUS MAMMALIAN CELL GROWTH ON TITANIUM-BASED MONO- AND BI-FUNCTIONAL COATINGS

    NARCIS (Netherlands)

    Subbiahdoss, Guruprakash; Pidhatika, Bidhari; Coullerez, Geraldine; Charnley, Mirren; Kuijer, Roel; van der Mei, Henny C.; Textor, Marcus; Busscher, Henk J.

    2010-01-01

    Biomaterials-associated-infections (BAI) are serious complications in modern medicine. Although non-adhesive coatings, like polymer-brush coatings, have been shown to prevent bacterial adhesion, they do not support cell growth. Bi-functional coatings are supposed to prevent biofilm formation while

  2. Production of medium-chain, a, omega-bifunctional monomers from fatty acids and n-alkanes

    NARCIS (Netherlands)

    Nuland, Youri M.

    2017-01-01

    In chapter 1, we give an introduction to bifunctional monomers that play an important role in the chemical industry. Briefly, the conventional production processes of α,ω-dicarboxylic acids and α,ω-diols are discussed. Strategies for more sustainable

  3. Dual actions of a novel bifunctional compound to lower glucose in mice with diet-induced insulin resistance.

    Science.gov (United States)

    Chen, Katherine; Jih, Alice; Kavaler, Sarah T; Lagakos, William S; Oh, Dayoung; Watkins, Steven M; Kim, Jane J

    2015-08-01

    Docosahexaenoic acid (DHA 22:6n-3) and salicylate are both known to exert anti-inflammatory effects. This study investigated the effects of a novel bifunctional drug compound consisting of DHA and salicylate linked together by a small molecule that is stable in plasma but hydrolyzed in the cytoplasm. The components of the bifunctional compound acted synergistically to reduce inflammation mediated via nuclear factor κB in cultured macrophages. Notably, oral administration of the bifunctional compound acted in two distinct ways to mitigate hyperglycemia in high-fat diet-induced insulin resistance. In mice with diet-induced obesity, the compound lowered blood glucose by reducing hepatic insulin resistance. It also had an immediate glucose-lowering effect that was secondary to enhanced glucagon-like peptide-1 (GLP-1) secretion and abrogated by the administration of exendin(9-39), a GLP-1 receptor antagonist. These results suggest that the bifunctional compound could be an effective treatment for individuals with type 2 diabetes and insulin resistance. This strategy could also be employed in other disease conditions characterized by chronic inflammation. Copyright © 2015 the American Physiological Society.

  4. Characterization of carbonaceous materials to be used for bifunctional air-electrodes in rechargeable zinc-air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Richner, R.; Bruesewitz, M.; Spahr, M.; Haas, O.

    2003-03-01

    Graphitized carbon blacks were investigated in terms of their stability in bifunctional air-electrodes. The long-term stability can be considerably enhanced by an appropriate graphitization of the original carbon black. Activation of the graphitized carbon blacks in air at elevated temperatures can improve the overpotential but may lead to a lower stability. (author)

  5. Biochemical Properties and Biological Function of a Monofunctional Microbial Biotin Protein Ligase

    Science.gov (United States)

    Daniels, Kyle G.; Beckett, Dorothy

    2010-01-01

    Biotin protein ligases constitute a family of enzymes that catalyze biotin linkage to biotin-dependent carboxylases. In bacteria these enzymes are functionally divided into two classes; the monofunctional enzymes that only catalyze biotin addition and the bifunctional enzymes that also bind to DNA to regulate transcription initiation. Biochemical and biophysical studies of the bifunctional Escherichia coli ligase suggest that several properties of the enzyme have evolved to support its additional regulatory role. Included among these properties are the order of substrate binding and linkage between oligomeric state and ligand binding. PMID:20499837

  6. Iminodiacetic acid as bifunctional linker for dimerization of cyclic RGD peptides.

    Science.gov (United States)

    Xu, Dong; Zhao, Zuo-Quan; Chen, Shu-Ting; Yang, Yong; Fang, Wei; Liu, Shuang

    2017-05-01

    In this study, I2P-RGD2 was used as the example to illustrate a novel approach for dimerization of cyclic RGD peptides. The main objective of this study was to explore the impact of bifunctional linkers (glutamic acid vs. iminodiacetic acid) on tumor-targeting capability and excretion kinetics of the 99mTc-labeled dimeric cyclic RGD peptides. HYNIC-I2P-RGD2 was prepared by reacting I2P-RGD2 with HYNIC-OSu in the presence of diisopropylethylamine, and was evaluated for its αvβ3 binding affinity against 125I-echistatin bound to U87MG glioma cells. 99mTc-I2P-RGD2 was prepared with high specific activity (~185GBq/μmol). The athymic nude mice bearing U87MG glioma xenografts were used to evaluate its biodistribution properties and image quality in comparison with those of 99mTc-3P-RGD2. The IC50 value for HYNIC-I2P-RGD2 was determined to be 39±6nM, which was very close to that (IC50=33±5nM) of HYNIC-3P-RGD2. Replacing glutamic acid with iminodiacetic acid had little impact on αvβ3 binding affinity of cyclic RGD peptides. 99mTc-I2P-RGD2 and 99mTc-3P-RGD2 shared similar tumor uptake values over the 2h period, and its αvβ3-specificity was demonstrated by a blocking experiment. The uptake of 99mTc-I2P-RGD2 was significantly lower than 99mTc-3P-RGD2 in the liver and kidneys. The U87MG glioma tumors were visualized by SPECT with excellent contrast using both 99mTc-I2P-RGD2 and 99mTc-3P-RGD2. Iminodiacetic acid is an excellent bifunctional linker for dimerization of cyclic RGD peptides. Bifunctional linkers have significant impact on the excretion kinetics of 99mTc radiotracers. Because of its lower liver uptake and better tumor/liver ratios, 99mTc-I2P-RGD2 may have advantages over 99mTc-3P-RGD2 for diagnosis of tumors in chest region. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Utilization of specific and non-specific peptide interactions with inorganic nanomaterials on the surface of bacteriophage M13: Methodologies towards phage supported bi-functional materials

    Science.gov (United States)

    Avery, Kendra Nicole

    Many types of organisms create a variety of nano and micro scale materials from precursors available in their surrounding environments by a process called biomineralization. As scientists begin to understand how these organisms utilize specific and non-specific interactions with a variety of biopolymers such as chitin, peptides, proteins and nucleic acids with these precursors to create inorganic/organic composite materials, they have begun to wonder about the synthesis of other types of non-biologically templated synthetic techniques that might be possible. Bioengineered organisms and biopolymers have begun to be used for these types of studies. A variety of selection techniques exist for discovering biopolymers with an affinity for a target material, however, one of the most notable is a technique called peptide phage display. This is a technique that utilizes a commercially available randomized peptide library attached at the tip of the filamentous bacteriophage M13. In this dissertation capabilities of bacteriophage M13 are explored in regard to the creation of bi-functional nano materials by exploiting both specific peptide interactions as well as non-specific peptide interactions on the surface of the organism. Chapter 2 focuses on utilizing the specific peptide interactions of the randomized library at pIII in order to discover peptides with high binding affinity for a variety of nanomaterials. Selection studies called biopanning are performed on a variety of nanomaterials such as CaMoO4, allotropes of Ni, Fe2O3 and Fe3O4, and Rh and Pt with the fcc type crystal structure. Similarities and differences between peptides discovered for these materials are discussed. Chapter 3 focuses on utilizing the non-specific peptide interactions on the long axis of M13 called pVIII. The pVIII region consists of 2700 copies of the same 50 amino acid protein which as a negatively charged domain which is exposed to solution. The pVIII region therefore provides the surface of

  8. A sustainable method inspired by nature for the production of original bi-functional nutraceuticals containing prebiotic fibers and highly bio-available forms of calcium and magnesium

    OpenAIRE

    Goffin, Dorothée; Blecker, Christophe; Paquot, Michel

    2012-01-01

    A sustainable method inspired by nature is proposed leading to an original bifunctional product active on gut health, metabolism regulation, immunity and mineral fortification, fighting against topical chronic diseases (type2 diabetes, osteoporosis, colon cancer…). Peer reviewed

  9. Fabrication of bifunctional core-shell Fe3O4 particles coated with ultrathin phosphor layer

    Science.gov (United States)

    Atabaev, Timur Sh; Kim, Hyung-Kook; Hwang, Yoon-Hwae

    2013-08-01

    Bifunctional monodispersed Fe3O4 particles coated with an ultrathin Y2O3:Tb3+ shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe3O4 core and outer Y2O3:Tb3+ shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging.

  10. Bi-functional biobased packing of the cassava starch, glycerol, licuri nanocellulose and red propolis.

    Directory of Open Access Journals (Sweden)

    Samantha Serra Costa

    Full Text Available The aim of this study was to characterize and determine the bi-functional efficacy of active packaging films produced with starch (4% and glycerol (1.0%, reinforced with cellulose nanocrystals (0-1% and activated with alcoholic extracts of red propolis (0.4 to 1.0%. The cellulose nanocrystals used in this study were extracted from licuri leaves. The films were characterized using moisture, water-activity analyses and water vapor-permeability tests and were tested regarding their total phenolic compounds and mechanical properties. The antimicrobial and antioxidant efficacy of the films were evaluated by monitoring the use of the active films for packaging cheese curds and butter, respectively. The cellulose nanocrystals increased the mechanical strength of the films and reduced the water permeability and water activity. The active film had an antimicrobial effect on coagulase-positive staphylococci in cheese curds and reduced the oxidation of butter during storage.

  11. Loss-of-function mutation in bi-functional marine bacterial sialyltransferase.

    Science.gov (United States)

    Kajiwara, Hitomi; Katayama, Sakurako; Kakuta, Yoshimitsu; Okino, Nozomu; Ito, Makoto; Mine, Toshiki; Yamamoto, Takeshi

    2012-01-01

    An α2,3-sialyltransferase produced by Photobacterium phosphoreum JT-ISH-467 is a bi-functional enzyme showing both α2,3-sialyltransferase and α2,3-linkage specific sialidase activity. To date, the crystal structures of several sialyltransferases have been solved, but the roles of amino acid residues around the catalytic site have not been completely clarified. Hence we performed a mutational study using α2,3-sialyltransferase cloned from P. phosphoreum JT-ISH-467 as a model enzyme to study the role of the amino acid residues around the substrate-binding site. It was found that a mutation of the glutamic acid at position 342 in the sialyltransferase resulted in a loss of sialidase activity, although the mutant showed no decrease in sialyltransferase activity. Based on this result, it is strongly expected that the Glu342 of the enzyme is an important amino acid residue for sialidase activity.

  12. Directed assembly of bifunctional silica-iron oxide nanocomposite with open shell structure.

    Science.gov (United States)

    Che, Hui Xin; Yeap, Swee Pin; Osman, Mohamed Syazwan; Ahmad, Abdul Latif; Lim, JitKang

    2014-10-08

    The synthesis of nanocomposite with controlled surface morphology plays a key role for pollutant removal from aqueous environments. The influence of the molecular size of the polyelectrolyte in synthesizing silica-iron oxide core-shell nanocomposite with open shell structure was investigated by using dynamic light scattering, atomic force microscopy, and quartz crystal microbalance with dissipation (QCM-D). Here, poly(diallydimethylammonium chloride) (PDDA) was used to promote the attachment of iron oxide nanoparticles (IONPs) onto the silica surface to assemble a nanocomposite with magnetic and catalytic bifunctionality. High molecular weight PDDA tended to adsorb on silica colloid, forming a more extended conformation layer than low molecular weight PDDA. Subsequent attachment of IONPs onto this extended PDDA layer was more randomly distributed, forming isolated islands with open space between them. By taking amoxicillin, an antibiotic commonly found in pharmaceutical waste, as the model system, better removal was observed for silica-iron oxide nanocomposite with a more extended open shell structure.

  13. Boehmite-An Efficient and Recyclable Acid-Base Bifunctional Catalyst for Aldol Condensation Reaction.

    Science.gov (United States)

    Reshma, P C Rajan; Vikneshvaran, Sekar; Velmathi, Sivan

    2018-06-01

    In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product. The scope of the reaction is extended for various substituted aldehydes. A probable mechanism has been suggested to explain the cooperative behavior of the acidic and basic sites. The catalyst is environmentally friendly and easily recovered from the reaction mixture. Also the catalyst is reusable up to 3 catalytic cycles.

  14. Pure blue-light emissive poly(oligofluorenes) with bifunctional poss in the main chain.

    Science.gov (United States)

    Chi, Hong; Lim, Siew Lay; Wang, Fuke; Wang, Xizu; He, Chaobin; Chin, Wee Shong

    2014-04-01

    Emission of conjugated polymers is known to undergo bathochromic shift from solution to film formation due to π-π stacking in the solid state. In this report, a series of pearl-necklace-like hybrid polymers is designed via the hydrosilylation condensation between bifunctional polyhedral oligomeric silsesquioxanes (B-POSS) and oligofluorene segments. Optoelectronic analyses unequivocally show that the presence of these interconnecting B-POSS can effectively reduce red-shift in photoluminescence and electroluminescence during film formation. These hybrid poly(oligofluorenes) display stable blue emission with high color purity. Thermal analyses also indicate that they are vitrified polymers with high glass transition temperature (up to 125 °C). We believe that this strategy can be extended to other conjugated systems to control color purity in electroactive materials and holds promise as new emissive materials for various applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Multi-domain terpenoid cyclase architecture and prospects for proximity in bifunctional catalysis.

    Science.gov (United States)

    Chen, Mengbin; Harris, Golda G; Pemberton, Travis A; Christianson, David W

    2016-12-01

    Crystal structures of terpenoid cyclases reveal assemblies of three basic domains designated α, β, and γ. While the biosynthesis of cyclic monoterpenes (C 10 ) and sesquiterpenes (C 15 ) most often involves enzymes with α or αβ domain architecture, the biosynthesis of cyclic diterpenes (C 20 ), sesterterpenes (C 25 ), and triterpenes (C 30 ) can involve enzymes with α, αα, βγ, or αβγ domain architecture. Indeed, some enzymes of terpenoid biosynthesis are bifunctional, with distinct active sites that catalyze sequential reactions. Interestingly, some of these enzymes oligomerize to form dimers, tetramers, and hexamers. Not only can such assemblies enable enzyme regulation by allostery, but they can also provide a modest enhancement of terpenoid product flux through proximity channeling or cluster channeling. The mixing and matching of functional terpenoid cyclase domains through tertiary and/or quaternary structure may also comprise an evolutionary strategy for facile product diversification. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Mono- and bi-functional arenethiols as surfactants for gold nanoparticles: synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Fratoddi Ilaria

    2011-01-01

    Full Text Available Abstract Stable gold nanoparticles stabilized by different mono and bi-functional arenethiols, namely, benzylthiol and 1,4-benzenedimethanethiol, have been prepared by using a modified Brust's two-phase synthesis. The size, shape, and crystalline structure of the gold nanoparticles have been determined by high-resolution electron microscopy and full-pattern X-ray powder diffraction analyses. Nanocrystals diameters have been tuned in the range 2 ÷ 9 nm by a proper variation of Au/S molar ratio. The chemical composition of gold nanoparticles and their interaction with thiols have been investigated by X-ray photoelectron spectroscopy. In particular, the formation of networks has been observed with interconnected gold nanoparticles containing 1,4-benzenedimethanethiol as ligand.

  17. Cage-like bifunctional chelators, copper-64 radiopharmaceuticals and PET imaging using the same

    Energy Technology Data Exchange (ETDEWEB)

    Conti, Peter S.; Cai, Hancheng; Li, Zibo; Liu, Shuanglong

    2016-08-02

    Disclosed is a class of versatile Sarcophagine based bifunctional chelators (BFCs) containing a hexa-aza cage for labeling with metals having either imaging, therapeutic or contrast applications radiolabeling and one or more linkers (A) and (B). The compounds have the general formula ##STR00001## where A is a functional group selected from group consisting of an amine, a carboxylic acid, an ester, a carbonyl, a thiol, an azide and an alkene, and B is a functional group selected from the group consisting of hydrogen, an amine, a carboxylic acid, and ester, a carbonyl, a thiol, an azide and an alkene. Also disclosed are conjugate of the BFC and a targeting moiety, which may be a peptide or antibody. Also disclosed are metal complexes of the BFC/targeting moiety conjugates that are useful as radiopharmaceuticals, imaging agents or contrast agents.

  18. Bifunctional nanoparticles for SERS monitoring and magnetic intervention of assembly and enzyme cutting of DNAs

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Liqin; Crew, Elizabeth; Yan, Hong; Shan, Shiyao; Skeete, Zakiya; Mott, Derrick; Krentsel, Tatiana; Yin, Jun; Chernova, Natasha A.; Luo, Jin; Engelhard, Mark H.; Wang, Chong M.; Li, Qingbiao; Zhong, Chuan-Jian

    2013-07-27

    The ability to detect and intervene in DNA assembly, disassembly, and enzyme cutting processes in a solution phase requires effective signal transduction and stimulus response. This report demonstrates a novel bifunctional strategy for the creation of this ability using gold- and silver-coated MnZn ferrite nanoparticles (MZF@Au or MZF@Ag) that impart magnetic and surfaceenhanced Raman scattering (SERS) functionalities to these processes. The double-stranded DNA linkage of labeled gold nanoparticles with MZF@Au (or MZF@Ag) produces interparticle "hot-spots" for real-time SERS monitoring of the DNA assembly, disassembly, or enzyme cutting processes, during which the magnetic component provides an effective means for intervention in the solution. The unique combination of the nanoprobes functionalities serves a new paradigm for the design of functional nanoprobes in biomolecular recognition and intervention.

  19. Synthesis of bifunctional receptor for fluoride and cadmium based on calix[4]arene with thiourea moieties

    Science.gov (United States)

    Quiroga-Campano, C.; Gómez-Machuca, H.; Moris, S.; Jara, P.; De la Fuente, J. R.; Pessoa-Mahana, H.; Jullian, C.; Saitz, C.

    2017-08-01

    A new calix[4]arene thiourea derivative bearing a benzothiazolyl moiety (L) was synthetized and characterized by single crystal X-ray, NMR and ESI-TOF. The binding ability of the bifunctional receptor towards several ions was investigated in acetonitrile by means of UV-Visible and NMR spectroscopy. The UV-Vis studies of receptor L demonstrated a stoichiometry of 1:1 for all ions studied. Also, recognize selectively F- and Cd2+ with a detection limit of 97 and 37 μM, respectively. Also, 1H NMR titration of receptor L indicated that both thiourea bridge and phenolic hydroxyl functional groups played a critical role in the binding of F- and Cd2+ ions. 1H NMR spectrum showed that receptor L has a flattened-cone conformation in solution that changes to a cone conformation in the presence of fluoride while cadmium maintained the initial conformation.

  20. Organocatalyzed asymmetric Michael addition by an efficient bifunctional carbohydrate-thiourea hybrid with mechanistic DFT analysis.

    Science.gov (United States)

    Azad, Chandra S; Khan, Imran A; Narula, Anudeep K

    2016-12-28

    A series of thiourea based bifunctional organocatalysts having d-glucose as a core scaffold were synthesized and examined as catalysts for the asymmetric Michael addition reaction of aryl/alkyl trans-β-nitrostyrenes over cyclohexanone and other Michael donors having active methylene. Excellent enantioselectivities (<95%), diastereoselectivities (<99%), and yields (<99%) were attained under solvent free conditions using 10 mol% of 1d0. The obtained results were explained through DFT calculations using the B3LYP/6-311G(d,p)//B3LYP/6-31G(d) basic set. The QM/MM calculations revealed the role of cyclohexanone as a solvent as well as reactant in the rate determining step imparting 31.91 kcal mol(-1) of energy towards the product formation.

  1. Preparation and Characterization of Silica-Coated Magnetic–Fluorescent Bifunctional Microspheres

    Directory of Open Access Journals (Sweden)

    Xiao Qi

    2009-01-01

    Full Text Available Abstract Bifunctional magnetic–fluorescent composite nanoparticles (MPQDs with Fe3O4MPs and Mn:ZnS/ZnS core–shell quantum dots (QDs encapsulated in silica spheres were synthesized through reverse microemulsion method and characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, vibration sample magnetometer, and photoluminescence (PL spectra. Our strategy could offer the following features: (1 the formation of Mn:ZnS/ZnS core/shell QDs resulted in enhancement of the PL intensity with respect to that of bare Mn:ZnS nanocrystals due to the effective elimination of the surface defects; (2 the magnetic nanoparticles were coated with silica, in order to reduce any detrimental effects on the QD PL by the magnetic cores; and (3 both Fe3O4MPs and Mn:ZnS/ZnS core–shell QDs were encapsulated in silica spheres, and the obtained MPQDs became water soluble. The experimental conditions for the silica coating on the surface of Fe3O4nanoparticles, such as the ratio of water to surfactant (R, the amount of ammonia, and the amount of tetraethoxysilane, on the photoluminescence properties of MPQDs were studied. It was found that the silica coating on the surface of Fe3O4could effectively suppress the interaction between the Fe3O4and the QDs under the most optimal parameters, and the emission intensity of MPQDs showed a maximum. The bifunctional MPQDs prepared under the most optimal parameters have a typical diameter of 35 nm and a saturation magnetization of 4.35 emu/g at room temperature and exhibit strong photoluminescence intensity.

  2. A Bifunctional Perovskite Promoter for Polysulfide Regulation toward Stable Lithium-Sulfur Batteries.

    Science.gov (United States)

    Kong, Long; Chen, Xiang; Li, Bo-Quan; Peng, Hong-Jie; Huang, Jia-Qi; Xie, Jin; Zhang, Qiang

    2017-11-27

    Lithium-sulfur (LiS) batteries are strongly considered as the next-generation rechargeable cells. However, both the shuttle of lithium polysulfides (LiPSs) and sluggish kinetics in random deposition of lithium sulfides (Li2 S) significantly degrade the capacity, rate performance, and cycling life of LiS cells. Herein, bifunctional Ba0.5 Sr0.5 Co0.8 Fe0.2 O3-δ perovskite nanoparticles (PrNPs) are proposed as a promoter to immobilize LiPSs and guide the deposition of Li2 S in a LiS cell. The oxygen vacancy in PrNPs increases the metal reactivity to anchor LiPSs, and co-existence of lithiophilic (O) and sulfiphilic (Sr) sites in PrNP favor the dual-bonding (LiO and SrS bonds) to anchor LiPSs. The high catalytic nature of PrNP facilitates the kinetics of LiPS redox reaction. The PrNP with intrinsic LiPS affinity serves as nucleation sites for Li2 S deposition and guides its uniform propagation. Therefore, the bifunctional LiPS promoter in LiS cell yields high rate performance and ultralow capacity decay rate of 0.062% (a quarter of pristine LiS cells). The proposed strategy to immobilize LiPSs, promotes the conversion of LiPS, and regulates deposition of Li2 S by an emerging perovskite promoter and is also expected to be applied in other energy conversion and storage devices based on multi-electron redox reactions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. VTC4 is a bifunctional enzyme that affects myoinositol and ascorbate biosynthesis in plants.

    Science.gov (United States)

    Torabinejad, Javad; Donahue, Janet L; Gunesekera, Bhadra N; Allen-Daniels, Matthew J; Gillaspy, Glenda E

    2009-06-01

    Myoinositol synthesis and catabolism are crucial in many multiceullar eukaryotes for the production of phosphatidylinositol signaling molecules, glycerophosphoinositide membrane anchors, cell wall pectic noncellulosic polysaccharides, and several other molecules including ascorbate. Myoinositol monophosphatase (IMP) is a major enzyme required for the synthesis of myoinositol and the breakdown of myoinositol (1,4,5)trisphosphate, a potent second messenger involved in many biological activities. It has been shown that the VTC4 enzyme from kiwifruit (Actinidia deliciosa) has similarity to IMP and can hydrolyze l-galactose 1-phosphate (l-Gal 1-P), suggesting that this enzyme may be bifunctional and linked with two potential pathways of plant ascorbate synthesis. We describe here the kinetic comparison of the Arabidopsis (Arabidopsis thaliana) recombinant VTC4 with d-myoinositol 3-phosphate (d-Ins 3-P) and l-Gal 1-P. Purified VTC4 has only a small difference in the V(max)/K(m) for l-Gal 1-P as compared with d-Ins 3-P and can utilize other related substrates. Inhibition by either Ca(2+) or Li(+), known to disrupt cell signaling, was the same with both l-Gal 1-P and d-Ins 3-P. To determine whether the VTC4 gene impacts myoinositol synthesis in Arabidopsis, we isolated T-DNA knockout lines of VTC4 that exhibit small perturbations in abscisic acid, salt, and cold responses. Analysis of metabolite levels in vtc4 mutants showed that less myoinositol and ascorbate accumulate in these mutants. Therefore, VTC4 is a bifunctional enzyme that impacts both myoinositol and ascorbate synthesis pathways.

  4. Peroxisomal. beta. -oxidation enzyme proteins in adrenoleukodystrophy: distinction between x-linked adrenoleukodystrophy and neonatal adrenoleukodystrophy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.W.; Watkins, P.A.; Osumi, T.; Hashimoto, T.; Moser, H.W.

    1987-03-01

    Very long chain fatty acids, which accumulate in plasma and tissues in x-linked adrenoleukodystrophy (ALD), neonatal ALD, and the Zellweger cerebrohepatorenal syndrome, are degraded by the peroxisomal ..beta..-oxidation pathway, consisting of acyl-CoA oxidase, the bifunctional enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase, and ..beta..-ketothiolase. A marked deficiency of all three enzyme proteins was reported in livers from patients with the Zellweger syndrome, a disorder in which peroxisomes are decreased or absent. Peroxisomes are not as markedly decreased in neonatal ALD and appear normal in x-linked ALD. Immunoblot analysis of the peroxisomal ..beta..-oxidation enzymes revealed an almost complete lack of the bifunctional enzymes in neonatal ALD liver, similar to the finding in Zellweger tissues. In contrast, acyl-CoA oxidase and ..beta..-ketothiolase were present in neonatal ALD liver, although the thiolase appeared to be in precursor form (2-3 kDa larger than the mature enzyme) in neonatal ALD. Unlike either neonatal ALD or Zellweger syndrome, all three peroxisomal ..beta..-oxidation enzymes were present in x-linked ALD liver. Despite the absence in neonatal ALD liver of bifunctional enzyme protein, its mRNA was detected by RNA blot analysis in fibroblasts from these patients. These observations suggest that lack of bifunctional enzyme protein in neonatal ALD results from either abnormal translation of the mRNA or degradation of the enzyme prior to its entry into peroxisomes.

  5. Cloning and analysis of a bifunctional methyltransferase/restriction endonuclease TspGWI, the prototype of a Thermus sp. enzyme family

    Directory of Open Access Journals (Sweden)

    Zylicz-Stachula Agnieszka

    2009-05-01

    Full Text Available Abstract Background Restriction-modification systems are a diverse class of enzymes. They are classified into four major types: I, II, III and IV. We have previously proposed the existence of a Thermus sp. enzyme family, which belongs to type II restriction endonucleases (REases, however, it features also some characteristics of types I and III. Members include related thermophilic endonucleases: TspGWI, TaqII, TspDTI, and Tth111II. Results Here we describe cloning, mutagenesis and analysis of the prototype TspGWI enzyme that recognises the 5'-ACGGA-3' site and cleaves 11/9 nt downstream. We cloned, expressed, and mutagenised the tspgwi gene and investigated the properties of its product, the bifunctional TspGWI restriction/modification enzyme. Since TspGWI does not cleave DNA completely, a cloning method was devised, based on amino acid sequencing of internal proteolytic fragments. The deduced amino acid sequence of the enzyme shares significant sequence similarity with another representative of the Thermus sp. family – TaqII. Interestingly, these enzymes recognise similar, yet different sequences in the DNA. Both enzymes cleave DNA at the same distance, but differ in their ability to cleave single sites and in the requirement of S-adenosylmethionine as an allosteric activator for cleavage. Both the restriction endonuclease (REase and methyltransferase (MTase activities of wild type (wt TspGWI (either recombinant or isolated from Thermus sp. are dependent on the presence of divalent cations. Conclusion TspGWI is a bifunctional protein comprising a tandem arrangement of Type I-like domains; particularly noticeable is the central HsdM-like module comprising a helical domain and a highly conserved S-adenosylmethionine-binding/catalytic MTase domain, containing DPAVGTG and NPPY motifs. TspGWI also possesses an N-terminal PD-(D/EXK nuclease domain related to the corresponding domains in HsdR subunits, but lacks the ATP-dependent translocase module

  6. Cloning and analysis of a bifunctional methyltransferase/restriction endonuclease TspGWI, the prototype of a Thermus sp. enzyme family.

    Science.gov (United States)

    Zylicz-Stachula, Agnieszka; Bujnicki, Janusz M; Skowron, Piotr M

    2009-05-29

    Restriction-modification systems are a diverse class of enzymes. They are classified into four major types: I, II, III and IV. We have previously proposed the existence of a Thermus sp. enzyme family, which belongs to type II restriction endonucleases (REases), however, it features also some characteristics of types I and III. Members include related thermophilic endonucleases: TspGWI, TaqII, TspDTI, and Tth111II. Here we describe cloning, mutagenesis and analysis of the prototype TspGWI enzyme that recognises the 5'-ACGGA-3' site and cleaves 11/9 nt downstream. We cloned, expressed, and mutagenised the tspgwi gene and investigated the properties of its product, the bifunctional TspGWI restriction/modification enzyme. Since TspGWI does not cleave DNA completely, a cloning method was devised, based on amino acid sequencing of internal proteolytic fragments. The deduced amino acid sequence of the enzyme shares significant sequence similarity with another representative of the Thermus sp. family - TaqII. Interestingly, these enzymes recognise similar, yet different sequences in the DNA. Both enzymes cleave DNA at the same distance, but differ in their ability to cleave single sites and in the requirement of S-adenosylmethionine as an allosteric activator for cleavage. Both the restriction endonuclease (REase) and methyltransferase (MTase) activities of wild type (wt) TspGWI (either recombinant or isolated from Thermus sp.) are dependent on the presence of divalent cations. TspGWI is a bifunctional protein comprising a tandem arrangement of Type I-like domains; particularly noticeable is the central HsdM-like module comprising a helical domain and a highly conserved S-adenosylmethionine-binding/catalytic MTase domain, containing DPAVGTG and NPPY motifs. TspGWI also possesses an N-terminal PD-(D/E)XK nuclease domain related to the corresponding domains in HsdR subunits, but lacks the ATP-dependent translocase module of the HsdR subunit and the additional domains that

  7. Imaging cancer using PET--the effect of the bifunctional chelator on the biodistribution of a (64)Cu-labeled antibody.

    Science.gov (United States)

    Dearling, Jason L J; Voss, Stephan D; Dunning, Patricia; Snay, Erin; Fahey, Frederic; Smith, Suzanne V; Huston, James S; Meares, Claude F; Treves, S Ted; Packard, Alan B

    2011-01-01

    Use of copper radioisotopes in antibody radiolabeling is challenged by reported loss of the radionuclide from the bifunctional chelator used to label the protein. The objective of this study was to investigate the relationship between the thermodynamic stability of the (64)Cu-complexes of five commonly used bifunctional chelators (BFCs) and the biodistribution of an antibody labeled with (64)Cu using these chelators in tumor-bearing mice. The chelators [S-2-(aminobenzyl)1,4,7-triazacyclononane-1,4,7-triacetic acid (p-NH(2)-Bn-NOTA): 6-[p-(bromoacetamido)benzyl]-1, 4, 8, 11-tetraazacyclotetradecane-N, N', N'', N'''-tetraacetic acid (BAT-6): S-2-(4-aminobenzyl)-1,4,7,10-tetraazacyclododocane tetraacetic acid (p-NH(2)-Bn-DOTA): 1,4,7,10-tetraazacyclododocane-N, N', N", N"'-tetraacetic acid (DOTA): and 1-N-(4-aminobenzyl)-3,6,10,13,16,19-hexaazabicyclo[6.6.6]eicosane-1,8-diamine (SarAr)] were conjugated to the anti-GD2 antibody ch14.18, and the modified antibody was labeled with (64)Cu and injected into mice bearing subcutaneous human melanoma tumors (M21) (n = 3-5 for each study). Biodistribution data were obtained from positron emission tomography images acquired at 1, 24 and 48 hours post-injection, and at 48 hours post-injection a full ex vivo biodistribution study was carried out. The biodistribution, including tumor targeting, was similar for all the radioimmunoconjugates. At 48 h post-injection, the only statistically significant differences in radionuclide uptake (p < 0.05) were between blood, liver, spleen and kidney. For example, liver uptake of [(64)Cu]ch14.18-p-NH(2)-Bn-NOTA was 4.74 ± 0.77 per cent of the injected dose per gram of tissue (%ID/g), and for [(64)Cu]ch14.18-SarAr was 8.06 ± 0.77 %ID/g. Differences in tumor targeting correlated with variations in tumor size rather than which BFC was used. The results of this study indicate that differences in the thermodynamic stability of these chelator-Cu(II) complexes were not associated with significant

  8. Probing the role of parasite-specific, distant structural regions on communication and catalysis in the bifunctional thymidylate synthase-dihydrofolate reductase from Plasmodium falciparum.

    Science.gov (United States)

    Dasgupta, Tina; Anderson, Karen S

    2008-02-05

    Plasmodium falciparum thymidylate synthase-dihydrofolate reductase (TS-DHFR) is an essential enzyme in nucleotide biosynthesis and a validated molecular drug target in malaria. Because P. falciparum TS and DHFR are highly homologous to their human counterparts, existing active-site antifolate drugs can have dose-limiting toxicities. In humans, TS and DHFR are two separate proteins. In P. falciparum, however, TS-DHFR is bifunctional, with both TS and DHFR active sites on a single polypeptide chain of the enzyme. Consequently, P. falciparum TS-DHFR contains unique distant or nonactive regions that might modulate catalysis: (1) an N-terminal tail and (2) a linker region tethering DHFR to TS, and encoding a crossover helix that forms critical electrostatic interactions with the DHFR active site. The role of these nonactive sites in the bifunctional P. falciparum TS-DHFR is unknown. We report the first in-depth, pre-steady-state kinetic characterization of the full-length, wild-type (WT) P. falciparum TS-DHFR enzyme and probe the role of distant, nonactive regions through mutational analysis. We show that the overall rate-limiting step in the WT P. falciparum TS-DHFR enzyme is TS catalysis. We further show that if TS is in an activated (liganded) conformation, the DHFR rate is 2-fold activated, from 60 s-1 to 130 s-1 in the WT enzyme. The TS rate is also reciprocally activated by approximately 1.5-fold if DHFR is in an activated, ligand-bound conformation. Mutations to the linker region affect neither catalytic rate nor domain-domain communication. Deletion of the N-terminal tail, although in a location remote from the active site, decreases the DHFR single rate and the bifunctional TS-DHFR rate by a factor of 2. The 2-fold activation of the DHFR rate by TS ligands remains intact, although even the activated N-terminal mutant has just half the DHFR activity of the WT enzyme. However, the reciprocal communication between TS active site and DHFR ligands is impaired in N

  9. Bifunctional quaternary ammonium compounds to inhibit biofilm growth and enhance performance for activated carbon air-cathode in microbial fuel cells

    Science.gov (United States)

    Li, Nan; Liu, Yinan; An, Jingkun; Feng, Cuijuan; Wang, Xin

    2014-12-01

    The slow diffusion of hydroxyl out of the catalyst layer as well as the biofouling on the surface of cathode are two problems affecting power for membrane-less air-cathode microbial fuel cells (MFCs). In order to solve both of them simultaneously, here we simply modify activated carbon air-cathode using a bifunctional quaternary ammonium compound (QAC) by forced evaporation. The maximum power density reaches 1041 ± 12 mW m-2 in an unbuffered medium (0.5 g L-1 NaCl), which is 17% higher than the control, probably due to the accelerated anion transport in the catalyst layer. After 2 months, the protein content reduced by a factor of 26 and the power density increases by 33%, indicating that the QAC modification can effectively inhibit the growth of cathodic biofilm and improve the stability of performance. The addition of NaOH and QAC epoxy have a negative effect on power production due to the clogging of pores in catalyst layer.

  10. The ERAD inhibitor Eeyarestatin I is a bifunctional compound with a membrane-binding domain and a p97/VCP inhibitory group.

    Directory of Open Access Journals (Sweden)

    Qiuyan Wang

    2010-11-01

    Full Text Available Protein homeostasis in the endoplasmic reticulum (ER has recently emerged as a therapeutic target for cancer treatment. Disruption of ER homeostasis results in ER stress, which is a major cause of cell death in cells exposed to the proteasome inhibitor Bortezomib, an anti-cancer drug approved for treatment of multiple myeloma and Mantle cell lymphoma. We recently reported that the ERAD inhibitor Eeyarestatin I (EerI also disturbs ER homeostasis and has anti-cancer activities resembling that of Bortezomib.Here we developed in vitro binding and cell-based functional assays to demonstrate that a nitrofuran-containing (NFC group in EerI is the functional domain responsible for the cytotoxicity. Using both SPR and pull down assays, we show that EerI directly binds the p97 ATPase, an essential component of the ERAD machinery, via the NFC domain. An aromatic domain in EerI, although not required for p97 interaction, can localize EerI to the ER membrane, which improves its target specificity. Substitution of the aromatic module with another benzene-containing domain that maintains membrane localization generates a structurally distinct compound that nonetheless has similar biologic activities as EerI.Our findings reveal a class of bifunctional chemical agents that can preferentially inhibit membrane-bound p97 to disrupt ER homeostasis and to induce tumor cell death. These results also suggest that the AAA ATPase p97 may be a potential drug target for cancer therapeutics.

  11. Directed supramolecular assembly of Cu(II)-based "paddlewheels" into infinite 1-D chains using structurally bifunctional ligands.

    Science.gov (United States)

    Aakeröy, Christer B; Schultheiss, Nate; Desper, John

    2006-04-07

    The construction of Cu(II)-containing supramolecular chains is achieved by combining suitable anionic ligands (for controlling the coordination geometry and for creating a neutral building block) with four new bifunctional ligands containing a metal-coordinating pyridyl site and a self-complementary hydrogen-bonding moiety. Seven crystal structures are presented and in each case, the copper(II) complex displays a "paddlewheel" arrangement, with four carboxylate ligands occupying the equatorial sites, leaving room for the bifunctional ligand to coordinate in the axial positions. The supramolecular chemistry, which organizes the coordination-complexes into the desired infinite 1-D chains, is driven by a combination of N-H...N and N-H...O hydrogen-bonds in five of the seven structures.

  12. Post-modified acid-base bifunctional MIL-101(Cr) for one-pot deacetalization-Knoevenagel reaction

    Science.gov (United States)

    Mu, Manman; Yan, Xilong; Li, Yang; Chen, Ligong

    2017-04-01

    A novel and convenient approach for the construction of the bifunctional MIL-101 material bearing sulfonic acid and amino groups was established via the post-synthetic modification. This material possesses high BET surface area (1446 m2/g) and large pore volume (0.77 cm3/g). Significantly, this material could serve as a bifunctional heterogeneous catalyst and was initially employed for one-pot deacetalization-Knoevenagel reaction, exhibiting excellent catalytic performance (yield 99.74%). More importantly, it can be easily recovered and reused at least three times. Finally, our proposed catalytic mechanism indicated that amino and the sulfonic acid groups played a synergistic effect on this one-pot deacetalization-Knoevenagel reaction.

  13. Post-modified acid-base bifunctional MIL-101(Cr) for one-pot deacetalization-Knoevenagel reaction

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Manman [Tianjin University, School of Science (China); Yan, Xilong; Li, Yang; Chen, Ligong, E-mail: lgchen@tju.edu.cn [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) (China)

    2017-04-15

    A novel and convenient approach for the construction of the bifunctional MIL-101 material bearing sulfonic acid and amino groups was established via the post-synthetic modification. This material possesses high BET surface area (1446 m{sup 2}/g) and large pore volume (0.77 cm{sup 3}/g). Significantly, this material could serve as a bifunctional heterogeneous catalyst and was initially employed for one-pot deacetalization-Knoevenagel reaction, exhibiting excellent catalytic performance (yield 99.74%). More importantly, it can be easily recovered and reused at least three times. Finally, our proposed catalytic mechanism indicated that amino and the sulfonic acid groups played a synergistic effect on this one-pot deacetalization-Knoevenagel reaction.

  14. Hydrophilic cobalt sulfide nanosheets as a bifunctional catalyst for oxygen and hydrogen evolution in electrolysis of alkaline aqueous solution.

    Science.gov (United States)

    Zhu, Mingchao; Zhang, Zhongyi; Zhang, Hu; Zhang, Hui; Zhang, Xiaodong; Zhang, Lixue; Wang, Shicai

    2018-01-01

    Hydrophilic medium and precursors were used to synthesize a hydrophilic electro-catalyst for overall water splitting. The cobalt sulfide (Co 3 S 4 ) catalyst exhibits a layered nanosheet structure with a hydrophilic surface, which can facilitate the diffusion of aqueous substrates into the electrode pores and towards the active sites. The Co 3 S 4 catalyst shows excellent bifunctional catalytic activity for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline solution. The assembled water electrolyzer based on Co 3 S 4 exhibits better performance and stability than that of Pt/C-RuO 2 catalyst. Thereforce the hydrophilic Co 3 S 4 is a highly promising bifunctional catalyst for the overall water splitting reaction. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Dynamics of tropomyosin in muscle fibers as monitored by saturation transfer EPR of bi-functional probe.

    Directory of Open Access Journals (Sweden)

    Roni F Rayes

    Full Text Available The dynamics of four regions of tropomyosin was assessed using saturation transfer electron paramagnetic resonance in the muscle fiber. In order to fully immobilize the spin probe on the surface of tropomyosin, a bi-functional spin label was attached to i,i+4 positions via cysteine mutagenesis. The dynamics of bi-functionally labeled tropomyosin mutants decreased by three orders of magnitude when reconstituted into "ghost muscle fibers". The rates of motion varied along the length of tropomyosin with the C-terminus position 268/272 being one order of magnitude slower then N-terminal domain or the center of the molecule. Introduction of troponin decreases the dynamics of all four sites in the muscle fiber, but there was no significant effect upon addition of calcium or myosin subfragment-1.

  16. Purification, crystallization and preliminary X-ray crystallographic analysis of rice bifunctional α-amylase/subtilisin inhibitor from Oryza sativa

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Hung [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Peng, Wen-Yan [Institute of Bioinformatics and Structural Biology, National Tsing-Hua University, Hsinchu 30013,Taiwan (China); Huang, Yen-Chieh [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Guan, Hong-Hsiang; Hsieh, Ying-Cheng [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Institute of Bioinformatics and Structural Biology, National Tsing-Hua University, Hsinchu 30013,Taiwan (China); Liu, Ming-Yih [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Chang, Tschining [Department of Hospitality Management, Nan Jeon Institute of Technology, Yen-Shui, Tainan 73746,Taiwan (China); Chen, Chun-Jung, E-mail: cjchen@nsrrc.org.tw [Life Science Group, Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076,Taiwan (China); Department of Physics, National Tsing-Hua University, Hsinchu 30013,Taiwan (China)

    2006-08-01

    The crystallization of rice α-amylase/subtilisin bifunctional inhibitor is reported. Rice bifunctional α-amylase/subtilisin inhibitor (RASI) can inhibit both α-amylase from larvae of the red flour beetle (Tribolium castaneum) and subtilisin from Bacillus subtilis. The synthesis of RASI is up-regulated during the late milky stage in developing seeds. The 8.9 kDa molecular-weight RASI from rice has been crystallized using the hanging-drop vapour-diffusion method. According to 1.81 Å resolution X-ray diffraction data from rice RASI crystals, the crystal belongs to space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 79.99, b = 62.95, c = 66.70 Å. Preliminary analysis indicates two RASI molecules in an asymmetric unit with a solvent content of 44%.

  17. ZIF-67 incorporated with carbon derived from pomelo peels: A highly efficient bifunctional catalyst for oxygen reduction/evolution reactions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao; Yin, Feng-Xiang; Chen, Biao-Hua; He, Xiao-Bo; Lv, Peng-Liang; Ye, Cai-Yun; Liu, Di-Jia

    2017-05-01

    Developing carbon catalyst materials using natural, abundant and renewable resources as precursors plays an increasingly important role in clean energy generation and environmental protection. In this work, N-doped pomelo-peel-derived carbon (NPC) materials were prepared using a widely available food waste-pomelo peels and melamine. The synthetic NPC exhibits well-defined porosities and a highly doped-N content (e.g. 6.38 at% for NPC-2), therefore affords excellent oxygen reduction reaction (ORR) catalytic activities in alkaline electrolytes. NPC was further integrated with ZIF-67 to form ZIF-67@NPC hybrids through solvothermal reactions. The hybrid catalysts show substantially enhanced ORR catalytic activities comparable to that of commercial 20 wa Pt/C. Furthermore, the catalysts also exhibit excellent oxygen evolution reaction (OER) catalytic activities. Among all prepared ZIF-67@NPC hybrids, the optimal composition with ZIF-67 to NPC ratio of 2:1 exhibits the best ORR and OER bifunctional catalytic performance and the smallest Delta E (E-OER@10 mA cm(-2)-E-ORR@-1 mA cm(-2)) value of 0.79 V. The catalyst also demonstrated desirable 4-electron transfer pathways and superior catalytic stabilities. The Co-N-4 in ZIF-67, electrochemical active surface area, and the strong interactions between ZIF-67 and NPC are attributed as the main contributors to the bifunctional catalytic activities. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activities and stabilities; consequently, this hybrid catalyst is among the best of the reported bifunctional electrocatalysts and is promising for use in metal-air batteries and fuel cells. (C) 2016 Elsevier B.V. All rights reserved.

  18. L-Threonine-derived novel bifunctional phosphine-sulfonamide catalyst-promoted enantioselective aza-morita-Baylis-Hillman reaction

    KAUST Repository

    Zhong, Fangrui

    2011-03-18

    A series of novel bifunctional phosphine-sulfonamide organic catalysts were designed and readily prepared from natural amino acids, and they were utilized to promote enantioselective aza-Morita-Baylis-Hillman (MBH) reactions. l-Threonine-derived phosphine-sulfonamide 9b was found to be the most efficient catalyst, affording the desired aza-MBH adducts in high yields and with excellent enantioselectivities. © 2011 American Chemical Society.

  19. Self-Supported 3D PdCu Alloy Nanosheets as a Bifunctional Catalyst for Electrochemical Reforming of Ethanol.

    Science.gov (United States)

    Zhao, Xiaojing; Dai, Lei; Qin, Qing; Pei, Fei; Hu, Chengyi; Zheng, Nanfeng

    2017-03-01

    3D PdCu alloy nanosheets exhibit enhanced electrocatalytic activity toward hydrogen evolution reaction and ethanol oxidation reaction in alkaline media. Simultaneous hydrogen and acetate production via a solar-powered cell for ethanol reforming has been fabricated using the nanosheets as bifunctional electrocatalysts. The device is promising for the production of both hydrogen and value-added chemicals using renewable energy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Quest for the Ncb-type Metal-Organic Framework Platform: A Bifunctional Ligand Approach Meets Net Topology Needs.

    Science.gov (United States)

    Chen, Di-Ming; Zhang, Nan-Nan; Tian, Jia-Yue; Liu, Chun-Sen; Du, Miao

    2017-07-03

    A custom-designed bifunctional ligand was used to connect an in situ formed Co3(OH) cluster affording a porous metal-organic framework, which represents the first case of ncb-type networks constructed from a single kind of ditopic ligand. Noticeably, the activated MOF shows high volumetric C2H2 uptake and excellent adsorption selectivity for C2H2/CO2 separation at room temperature with a low sorption heat.

  1. Highly active and durable core-corona structured bifunctional catalyst for rechargeable metal-air battery application.

    Science.gov (United States)

    Chen, Zhu; Yu, Aiping; Higgins, Drew; Li, Hui; Wang, Haijiang; Chen, Zhongwei

    2012-04-11

    A new class of core-corona structured bifunctional catalyst (CCBC) consisting of lanthanum nickelate centers supporting nitrogen-doped carbon nanotubes (NCNT) has been developed for rechargeable metal-air battery application. The nanostructured design of the catalyst allows the core and corona to catalyze the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. These materials displayed exemplary OER and ORR activity through half-cell testing, comparable to state of the art commercial lanthanum nickelate (LaNiO(3)) and carbon-supported platinum (Pt/C), with added bifunctional capabilities allowing metal-air battery rechargeability. LaNiO(3) and Pt/C are currently the most accepted benchmark electrocatalyst materials for the OER and ORR, respectively; thus with comparable activity toward both of these reactions, CCBC are presented as a novel, inexpensive catalyst component for the cathode of rechargeable metal-air batteries. Moreover, after full-range degradation testing (FDT) CCBC retained excellent activity, retaining 3 and 13 times greater ORR and OER current upon comparison to state of the art Pt/C. Zinc-air battery performances of CCBC is in good agreement with the half-cell experiments with this bifunctional electrocatalyst displaying high activity and stability during battery discharge, charge, and cycling processes. Owing to its outstanding performance toward both the OER and ORR, comparable with the highest performing commercial catalysts to date for each of the respective reaction, coupled with high stability and rechargeability, CCBC is presented as a novel class of bifunctional catalyst material that is very applicable to future generation rechargeable metal-air batteries. © 2012 American Chemical Society

  2. Synergistic bifunctional catalyst design based on perovskite oxide nanoparticles and intertwined carbon nanotubes for rechargeable zinc-air battery applications.

    Science.gov (United States)

    Lee, Dong Un; Park, Hey Woong; Park, Moon Gyu; Ismayilov, Vugar; Chen, Zhongwei

    2015-01-14

    Advanced morphology of intertwined core-corona structured bifunctional catalyst (IT-CCBC) is introduced where perovskite lanthanum nickel oxide nanoparticles (LaNiO3 NP) are encapsulated by high surface area network of nitrogen-doped carbon nanotubes (NCNT) to produce highly active and durable bifunctional catalyst for rechargeable metal-air battery applications. The unique composite morphology of IT-CCBC not only enhances the charge transport property by providing rapid electron-conduction pathway but also facilitates in diffusion of hydroxyl and oxygen reactants through the highly porous framework. Confirmed by electrochemical half-cell testing, IT-CCBC in fact exhibits very strong synergy between LaNiO3 NP and NCNT demonstrating bifunctionality with significantly improved catalytic activities of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Furthermore, when compared to the state-of-art catalysts, IT-CCBC outperforms Pt/C and Ir/C in terms of ORR and OER, respectively, and shows improved electrochemical stability compared to them after cycle degradation testing. The practicality of the catalyst is corroborated by testing in a realistic rechargeable zinc-air battery utilizing atmospheric air in ambient conditions, where IT-CCBC demonstrates superior charge and discharge voltages and long-term cycle stability with virtually no battery voltage fading. These improved electrochemical properties of the catalyst are attributed to the nanosized dimensions of LaNiO3 NP controlled by simple hydrothermal technique, which enables prolific growth of and encapsulation by highly porous NCNT network. The excellent electrochemical results presented in this study highlight IT-CCBC as highly efficient and commercially viable bifunctional catalyst for rechargeable metal-air battery applications.

  3. Multicomponent synthesis of diverse pyrano-fused benzophenazines using bifunctional thiourea-based organocatalyst in aqueous medium.

    Science.gov (United States)

    Bharti, Ruchi; Parvin, Tasneem

    2016-11-01

    A series of pyrano-fused benzophenazines were synthesized using a bifunctional thiourea-based organocatalyst from the one-pot four-component reaction of 2-hydroxy-1,4-naphthoquinone, benzene-1,2-diamines, malononitrile or its derivatives and isatins or aromatic aldehydes in aqueous medium. Metal-free reaction condition, water as solvent, high bond forming efficiency (five new bonds formed in one step), good yields and easy purification process are the notable features of this methodology.

  4. Nanocarbon/oxide composite catalysts for bifunctional oxygen reduction and evolution in reversible alkaline fuel cells: A mini review

    Science.gov (United States)

    Chen, Mengjie; Wang, Lei; Yang, Haipeng; Zhao, Shuai; Xu, Hui; Wu, Gang

    2018-01-01

    A reversible fuel cell (RFC), which integrates a fuel cell with an electrolyzer, is similar to a rechargeable battery. This technology lies on high-performance bifunctional catalysts for the oxygen reduction reaction (ORR) in the fuel cell mode and the oxygen evolution reaction (OER) in the electrolyzer mode. Current catalysts are platinum group metals (PGM) such as Pt and Ir, which are expensive and scarce. Therefore, it is highly desirable to develop PGM-free catalysts for large-scale application of RFCs. In this mini review, we discussed the most promising nanocarbon/oxide composite catalysts for ORR/OER bifunctional catalysis in alkaline media, which is mainly based on our recent progress. Starting with the effectiveness of selected oxides and nanocarbons in terms of their activity and stability, we outlined synthetic methods and the resulting structures and morphologies of catalysts to provide a correlation between synthesis, structure, and property. A special emphasis is put on understanding of the possible synergistic effect between oxide and nanocarbon for enhanced performance. Finally, a few nanocomposite catalysts are discussed as typical examples to elucidate the rules of designing highly active and durable bifunctional catalysts for RFC applications.

  5. Structure of the Bifunctional Acyltransferase/Decarboxylase LnmK from the Leinamycin Biosynthetic Pathway Revealing Novel Activity for a Double-Hot-Dog Fold

    Energy Technology Data Exchange (ETDEWEB)

    Lohman, Jeremy R. [Scripps Research Inst., Jupiter, FL (United States); Bingman, Craig A. [Univ. of Wisconsin, Madison, WI (United States); Phillips Jr., George N. [Univ. of Wisconsin, Madison, WI (United States); Rice Univ., Houston, TX (United States); Shen, Ben [Scripps Research Inst., Jupiter, FL (United States)

    2013-01-15

    The β-branched C3 unit in leinamycin biosynthesis is installed by a set of four proteins, LnmFKLM. In vitro biochemical investigation confirmed that LnmK is a bifunctional acyltransferase/decarboxylase (AT/DC) that catalyzes first self-acylation using methylmalonyl-CoA as a substrate and subsequently transacylation of the methylmalonyl group to the phosphopantetheinyl group of the LnmL acyl carrier protein [Liu, T., Huang, Y., and Shen, B. (2009) J. Am. Chem. Soc. 131, 6900–6901]. LnmK shows no sequence homology to proteins of known function, representing a new family of AT/DC enzymes. Here we report the X-ray structure of LnmK. LnmK is homodimer with each of the monomers adopting a double-hot-dog fold. Cocrystallization of LnmK with methylmalonyl-CoA revealed an active site tunnel terminated by residues from the dimer interface. But, to canonical AT and ketosynthase enzymes that employ Ser or Cys as an active site residue, none of these residues are found in the vicinity of the LnmK active site. Instead, three tyrosines were identified, one of which, Tyr62, was established, by site-directed mutagenesis, to be the most likely active site residue for the AT activity of LnmK. Moreover, LnmK represents the first AT enzyme that employs a Tyr as an active site residue and the first member of the family of double-hot-dog fold enzymes that displays an AT activity known to date. The LnmK structure sets the stage for probing of the DC activity of LnmK through site-directed mutagenesis. These findings highlight natural product biosynthetic machinery as a rich source of novel enzyme activities, mechanisms, and structures.

  6. Activating the Bifunctionality of a Perovskite Oxide toward Oxygen Reduction and Oxygen Evolution Reactions.

    Science.gov (United States)

    Lyu, Yu-Qi; Ciucci, Francesco

    2017-10-18

    This article presents a facile and effective approach to activate the bifunctionality of calcium-manganese perovskites toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). We substituted Nb into the Mn site of CaMnO3 (CMO) and treated the material with H2. The as-obtained CaMn0.75Nb0.25O3-δ (H2-CMNO) displays the same structure as that of CMO, and compared to that of CMO, H2-CMNO exhibits significantly improved OER performance, including a lower overpotential, a reduced Tafel slope, a higher mass activity, and enhanced stability. In addition, the ORR performance of H2-CMNO is also greatly enhanced, relative to CMO, with a higher ORR activity and a more efficient electron-transfer pathway. H2-CMNO shows an even higher activity-per-catalyst cost and superior stability than that of state-of-the-art materials, such as IrO2 and Pt/C. This great enhancement in ORR and OER activity of H2-CMNO is attributed to several factors, including phase stabilization, optimized eg filling, better OH- adsorption, and improved electrical conductivity.

  7. Photoluminescent lead(II) coordination polymers stabilised by bifunctional organoarsonate ligands

    Science.gov (United States)

    Lin, Jian-Di; Onet, Camelia I.; Schmitt, Wolfgang

    2015-04-01

    Four lead(II) coordination polymers were isolated under hydro(solvo)thermal conditions. The applied synthetic methodology takes advantage of the coordination behaviour of a new bifunctional organoarsonate ligand, 4-(1, 2, 4-triazol-4-yl)phenylarsonic acid (H2TPAA) and involves the variation of lead(II) reactants, metal/ligand mole ratios, and solvents. The constitutional composition of the four lead(II) coordination polymers can be formulated as [Pb2(TPAA)(HTPAA)(NO3)]·6H2O (1), [Pb2(TPAA)(HTPAA)2]·DMF·0.5H2O (DMF = N, N-Dimethylformamide) (2), [Pb2Cl2(TPAA)H2O] (3), and [Pb3Cl(TPAA)(HTPAA)2H2O]Cl (4). The compounds were characterized by single-crystal and powder x-ray diffraction techniques, thermogravimetric analyses, infra-red spectroscopy, and elemental analyses. Single-crystal x-ray diffraction reveals that 1 and 2 represent two-dimensional (2D) layered structures whilst 3 and 4 form three-dimensional (3D) frameworks. The structures of 1, 2, and 4 contain one-dimensional (1D) {PbII/AsO3} substructures, while 3 is composed of 2D {PbII/AsO3} arrays. Besides their interesting topologies, 1-4 all exhibit photoluminescence properties in the solid state at room temperature.

  8. A self-cleaning Li-S battery enabled by a bifunctional redox mediator

    Science.gov (United States)

    Ren, Y. X.; Zhao, T. S.; Liu, M.; Zeng, Y. K.; Jiang, H. R.

    2017-09-01

    The polysulfide shuttle effect and lithium dendrite growth in lithium-sulfur (Li-S) batteries can repeatedly breach the anodic solid electrolyte interphase (SEI) over cycling. As a result, irreversible short-chain sulfide side products (Li2Sx, x = 1, 2) keep depositing on the Li anode, leading to the active material loss, increasing the Li+ transport resistance, and thereby reducing the cycle life. In this work, indium iodide (InI3) is investigated as a bifunctional electrolyte additive for Li-S batteries to protect the Li anode and decompose the side products spontaneously. On the one hand, Indium (In) is electrodeposited onto the Li anode prior to Li plating during the initial charging process, forming a chemically and mechanically stable SEI to prevent the Li anode from reacting with soluble polysulfide species to form Li2Sx (x = 1, 2) side products. On the other hand, by adequately overcharging the battery, the triiodide/iodide redox mediator is capable of chemically transforming side products deposited on the Li anode and separator into soluble polysulfides, which can be recycled by the cathode. It is shown that the battery with the InI3 additive exhibits a prolonged cycle life, and is capable of retrieving its capacity by a facile overcharging process.

  9. A Bifunctional Fluorogenic Rhodamine Probe for Proximity-Induced Bioorthogonal Chemistry.

    Science.gov (United States)

    Werther, Philipp; Möhler, Jasper S; Wombacher, Richard

    2017-10-16

    Bioorthogonal reactions have emerged as a versatile tool in life sciences. The inverse electron demand Diels-Alder reaction (DAinv) stands out due to the availability of reactants with very fast kinetics. However, highly reactive dienophiles suffer the disadvantage of being less stable and prone to side reactions. Here, we evaluate the extent of acceleration of rather unreactive but highly stable dienophiles by DNA-templated proximity. To this end, we developed a modular synthetic route for a novel bifunctional fluorogenic tetrazine rhodamine probe that we used to determine the reaction kinetics of various dienophiles in a fluorescence assay. Under proximity-driven conditions the reaction was found to be several orders of magnitude faster, and we observed almost no background reaction when proximity was not induced. This fundamental study identifies a minimally sized fluorogenic tetrazine dienophile reactant pair that has potential to be generally used for the visualization of biomolecular interactions with temporal and spatial resolution in living systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Herinase: a novel bi-functional fibrinolytic protease from the monkey head mushroom, Hericium erinaceum.

    Science.gov (United States)

    Choi, Bong-Suk; Sapkota, Kumar; Choi, Jun-Hui; Shin, Chang-ho; Kim, Seung; Kim, Sung-Jun

    2013-06-01

    Herinase, a new bi-functional fibrinolytic metalloprotease, was purified from a medicinal and edible mushroom Hericium erinaceum. The enzyme was monomeric with a molecular mass of 51 kDa. Analysis of fibrin zymography showed an active band with a similar molecular mass. The N-terminal sequence of herinase VPSSFRTTITDAQLRG was highly distinguished from known fibrinolytic enzymes. Moreover, the enzyme activity was strongly inhibited by EDTA and EGTA, indicating that herinase is a metalloprotease. Herinase exhibited high specificity for the substrate t-PA followed by plasmin. The K(m) and V(max) values for H-D-Ile-Pro-Arg-PNA were found to be 4.7 mg and 26.7 U/ml respectively. Similarly, fibrin plate assays revealed that it was able to degrade fibrin clot directly and also able to activate plasminogen. Herinase provoked a rapid degradation of fibrin and fibrinogen α chains and slower degradation of γ chains. It had no activity on the β chains of fibrin and fibrinogen. This result suggests that herinase could possibly contain higher amount of α-fibrinogenase. The activity of herinase was stimulated by metal ions such as Ca(2+), Mg(2+), and Mn(2+), but inhibited by Cu(2+), Fe(2+), and Zn(2+). Herinase exhibited maximum activity at 30 °C and pH 7.0. These results demonstrate that herinase could be a novel fibrinolytic enzyme.

  11. Direct conversion of CO2 into liquid fuels with high selectivity over a bifunctional catalyst

    Science.gov (United States)

    Gao, Peng; Li, Shenggang; Bu, Xianni; Dang, Shanshan; Liu, Ziyu; Wang, Hui; Zhong, Liangshu; Qiu, Minghuang; Yang, Chengguang; Cai, Jun; Wei, Wei; Sun, Yuhan

    2017-10-01

    Although considerable progress has been made in carbon dioxide (CO2) hydrogenation to various C1 chemicals, it is still a great challenge to synthesize value-added products with two or more carbons, such as gasoline, directly from CO2 because of the extreme inertness of CO2 and a high C-C coupling barrier. Here we present a bifunctional catalyst composed of reducible indium oxides (In2O3) and zeolites that yields a high selectivity to gasoline-range hydrocarbons (78.6%) with a very low methane selectivity (1%). The oxygen vacancies on the In2O3 surfaces activate CO2 and hydrogen to form methanol, and C-C coupling subsequently occurs inside zeolite pores to produce gasoline-range hydrocarbons with a high octane number. The proximity of these two components plays a crucial role in suppressing the undesired reverse water gas shift reaction and giving a high selectivity for gasoline-range hydrocarbons. Moreover, the pellet catalyst exhibits a much better performance during an industry-relevant test, which suggests promising prospects for industrial applications.

  12. Engineering the robustness of Saccharomyces cerevisiae by introducing bifunctional glutathione synthase gene.

    Science.gov (United States)

    Qiu, Zhiqi; Deng, Zujun; Tan, Hongming; Zhou, Shining; Cao, Lixiang

    2015-04-01

    Robust, high-yielding Saccharomyces cerevisiae is highly desirable for cost-effective cellulosic ethanol production. In this study, the bifunctional glutathione (GSH) synthetase genes GCSGS at high copy number was integrated into ribosomal DNA of S. cerevisiae by Cre-LoxP system. Threefold higher GSH contents (54.9 μmol/g dry weight) accumulated in the engineered strain BY-G compared to the reference strain. Tolerance of BY-G to H2O2 (3 mM), temperature (40 °C), furfural (10 mM), hydroxymethylfurfural (HMF, 10 mM) and 0.5 mM Cd(2+) increased compared to reference strain. Twofold higher ethanol concentration was obtained by BY-G in simultaneous saccharification and fermentation of corn stover compared to the reference strain. The results showed that intracellular GSH content of S. cerevisiae has an influence on robustness. The strategy is used to engineer S. cerevisiae strains adaptive to a combination of tolerance to inhibitors and raised temperature that may occur in high solid simultaneous saccharification and fermentation of lignocellulosic feedstocks.

  13. Deoxyribonuclease I footprinting reveals different DNA binding modes of bifunctional platinum complexes.

    Science.gov (United States)

    Chválová, Katerina; Kaspárková, Jana; Farrell, Nicholas; Brabec, Viktor

    2006-08-01

    Deoxyribonuclease I (DNase I) footprinting methodology was used to analyze oligodeoxyribonucleotide duplexes containing unique and single, site-specific adducts of trinuclear bifunctional platinum compound, [{trans-PtCl(NH3)2}2 mu-trans-Pt(NH3)2{H2N(CH2)6NH2}2]4+ (BBR3464) and the results were compared with DNase I footprints of some adducts of conventional mononuclear cis-diamminedichloroplatinum(II) (cisplatin). These examinations took into account the fact that the local conformation of the DNA at the sites of the contacts of DNase I with DNA phosphates, such as the minor groove width and depth, sequence-dependent flexibility and bendability of the double helix, are important determinants of sequence-dependent binding to and cutting of DNA by DNase I. It was shown that various conformational perturbations induced by platinum binding in the major groove translated into the minor groove, allowing their detection by DNase I probing. The results also demonstrate the very high sensitivity of DNase I to DNA conformational alterations induced by platinum complexes so that the platinum adducts which induce specific local conformational alterations in DNA are differently recognized by DNase I.

  14. "Click" chemistry mildly stabilizes bifunctional gold nanoparticles for sensing and catalysis.

    Science.gov (United States)

    Li, Na; Zhao, Pengxiang; Liu, Na; Echeverria, María; Moya, Sergio; Salmon, Lionel; Ruiz, Jaime; Astruc, Didier

    2014-07-01

    A large family of bifunctional 1,2,3-triazole derivatives that contain both a polyethylene glycol (PEG) chain and another functional fragment (e.g., a polymer, dendron, alcohol, carboxylic acid, allyl, fluorescence dye, redox-robust metal complex, or a β-cyclodextrin unit) has been synthesized by facile "click" chemistry and mildly coordinated to nanogold particles, thus providing stable water-soluble gold nanoparticles (AuNPs) in the size range 3.0-11.2 nm with various properties and applications. In particular, the sensing properties of these AuNPs are illustrated through the detection of an analogue of a warfare agent (i.e., sulfur mustard) by means of a fluorescence "turn-on" assay, and the catalytic activity of the smallest triazole-AuNPs (core of 3.0 nm) is excellent for the reduction of 4-nitrophenol in water. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Bifunctional Hydrogels Containing the Laminin Motif IKVAV Promote Neurogenesis.

    Science.gov (United States)

    Farrukh, Aleeza; Ortega, Felipe; Fan, Wenqiang; Marichal, Nicolás; Paez, Julieta I; Berninger, Benedikt; Campo, Aránzazu Del; Salierno, Marcelo J

    2017-09-28

    Engineering of biomaterials with specific biological properties has gained momentum as a means to control stem cell behavior. Here, we address the effect of bifunctionalized hydrogels comprising polylysine (PL) and a 19-mer peptide containing the laminin motif IKVAV (IKVAV) on embryonic and adult neuronal progenitor cells under different stiffness regimes. Neuronal differentiation of embryonic and adult neural progenitors was accelerated by adjusting the gel stiffness to 2 kPa and 20 kPa, respectively. While gels containing IKVAV or PL alone failed to support long-term cell adhesion, in bifunctional gels, IKVAV synergized with PL to promote differentiation and formation of focal adhesions containing β1-integrin in embryonic cortical neurons. Furthermore, in adult neural stem cell culture, bifunctionalized gels promoted neurogenesis via the expansion of neurogenic clones. These data highlight the potential of synthetic matrices to steer stem and progenitor cell behavior via defined mechano-adhesive properties. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  16. Uncommon Pyrazoyl-Carboxyl Bifunctional Ligand-Based Microporous Lanthanide Systems: Sorption and Luminescent Sensing Properties.

    Science.gov (United States)

    Li, Gao-Peng; Liu, Ge; Li, Yong-Zhi; Hou, Lei; Wang, Yao-Yu; Zhu, Zhonghua

    2016-04-18

    Seven new isostructural lanthanide metal-organic frameworks (Ln-MOFs), [Ln(Hpzbc)2(NO3)]·H2O (1-Ln, Ln = Nd(3+), Sm(3+), Eu(3+), Gd(3+), Tb(3+), Er(3+), and Yb(3+) ions, H2pzbc = 3-(1H-pyrazol-3-yl) benzoic acid), with one-dimensional (1D) channels decorated by nitrate anions and pyrazoyl groups have been constructed. 1-Ln, as revealed by structural analysis, represent uncommon microporous 3D Ln-pyrazoyl-carboxyl systems using pyrazoyl-carboxyl bifunctional ligands as bridges. The luminescent investigations show that 1-Eu is an excellent MOF-based fluorescent probe, with high sensitivity, selectivity, and simple regeneration, for environmentally relevant Fe(3+) and Cr2O7(2-) ions. 1-Eu also presents highly selective capture for CO2 over N2 and CH4 due to the multiple binding sites for CO2 molecules, which were supported by Grand Canonical Monte Carlo (GCMC) simulations.

  17. Two new inorganic-organic hybrid single pendant hexadecavanadate derivatives with bifunctional electrocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Baoxia [Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Peng, Jun [Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)]. E-mail: jpeng@nenu.edu.cn; Tian, Aixiang [Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Sha, Jingquan [Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Li, Li [Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China); Liu, Hongsheng [Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)

    2007-03-01

    Two new supramolecular assembly hexadecavanadate derivatives of H{sub 2}[Cd(phen){sub 3}]{sub 2}{l_brace}[Cd(H{sub 2}O)(phen){sub 2}](V{sub 16}O{sub 38}Cl){r_brace}.2.5H{sub 2}O 1 (phen = 1,10'-phenanthroline) and H{sub 2}[Cd(bipy){sub 3}][Cd(H{sub 2}O)(bipy){sub 2}]{l_brace}[Cd(H{sub 2}O)(bipy){sub 2}](V{sub 16}O{sub 38}Cl){r_brace}.1.5H{sub 2}O 2 (bipy 2,2'-bipyridine), have been prepared under mild hydrothermal conditions and structurally characterized by IR, XPS spectra, TG analyses and single-crystal X-ray diffraction. Compounds 1 and 2 are constructed from single pendant [CdL{sub 2}] (L = phen, 1 and L = bipy, 2) modified hexadecavanadates. The hybrids 1 and 2 were used as solid bulk modifier to fabricate bulk-modified carbon paste electrodes (CPEs) (1-CPE and 2-CPE) by direct mixing. The electrochemical behaviors and electrocatalysis of 1-CPE and 2-CPE indicate bifunctional electrocatalytic activities toward both the oxidation and reduction of nitrite. Furthermore, their electrocatalytic activities toward the reduction of bromate and oxidation of ascorbic acid are also studied in 1 M H{sub 2}SO{sub 4} aqueous solutions.

  18. Highly Active and Durable Nanocrystal-Decorated Bifunctional Electrocatalyst for Rechargeable Zinc-Air Batteries.

    Science.gov (United States)

    Lee, Dong Un; Park, Moon Gyu; Park, Hey Woong; Seo, Min Ho; Wang, Xiaolei; Chen, Zhongwei

    2015-09-21

    A highly active and durable bifunctional electrocatalyst that consists of cobalt oxide nanocrystals (Co3 O4 NC) decorated on the surface of N-doped carbon nanotubes (N-CNT) is introduced as effective electrode material for electrically rechargeable zinc-air batteries. This active hybrid catalyst is synthesized by a facile surfactant-assisted method to produce Co3 O4 NC that are then decorated on the surface of N-CNT through hydrophobic attraction. Confirmed by half-cell testing, Co3 O4 NC/N-CNT demonstrates superior oxygen reduction and oxygen evolution catalytic activities and has a superior electrochemical stability compared to Pt/C and Ir/C. Furthermore, rechargeable zinc-air battery testing of Co3 O4 NC/N-CNT reveals superior galvanodynamic charge and discharge voltages with a significantly extended cycle life of over 100 h, which suggests its potential as a replacement for precious-metal-based catalysts for electric vehicles and grid energy storage applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Designing calcium phosphate-based bifunctional nanocapsules with bone-targeting properties

    Energy Technology Data Exchange (ETDEWEB)

    Khung, Yit-Lung; Bastari, Kelsen; Cho, Xing Ling; Yee, Wu Aik; Loo, Say Chye Joachim, E-mail: joachimloo@ntu.edu.sg [Nanyang Technological University, School of Materials Science and Engineering (Singapore)

    2012-06-15

    Using sodium dodecyl sulphate micelles as template, hollow-cored calcium phosphate nanocapsules were produced. The surfaces of the nanocapsule were subsequently silanised by a polyethylene glycol (PEG)-based silane with an N-hydroxysuccinimide ester end groups which permits for further attachment with bisphosphonates (BP). Characterisations of these nanocapsules were investigated using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy, Fourier Transform Infra-Red Spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Dynamic Light Scattering. To further validate the bone-targeting potential, dentine discs were incubated with these functionalised nanocapsules. FESEM analysis showed that these surface-modified nanocapsules would bind strongly to dentine surfaces compared to non-functionalised nanocapsules. We envisage that respective components would give this construct a bifunctional attribute, whereby (1) the shell of the calcium phosphate nanocapsule would serve as biocompatible coating aiding in gradual osteoconduction, while (2) surface BP moieties, acting as targeting ligands, would provide the bone-targeting potential of these calcium phosphate nanocapsules.

  20. Colorimetric and luminescent bifunctional iridium(III) complexes for the sensitive recognition of cyanide ions

    Science.gov (United States)

    Chen, Xiudan; Wang, Huili; Li, Jing; Hu, Wenqin; Li, Mei-Jin

    2017-02-01

    Two new cyclometalated iridium(III) complexes [(ppy)2Irppz]Cl (1) and [(ppy)2Irbppz]Cl (2) (where ppy = 2-phenylpyridine, ppz = 4,7-phenanthrolino-5,6:5,6-pyrazine, bppz = 2.3-di-2-pyridylpyrazine), were designed and synthesized. The structure of [(ppy)2Irppz]Cl was determined by single crystal X-ray diffraction. Their photophysical properties were also studied. This kind of complexes could coordinate with Cu2 +, the photoluminescence (PL) of the complex was quenched, and the color changed from orange-red to green. The forming M-Cu (M: complexes 1 and 2) ensemble could be further utilized as a colorimetric and emission ;turn-on; bifunctional detection for CN-, especially for complex 1-Cu2 + showed a high sensitivity toward CN- with a limit of diction is 97 nM. Importantly, this kind of iridium(III) complexes shows a unique recognition of cyanide ions over other anions which makes it an eligible sensing probe for cyanide ions.

  1. Bifunctional separator as a polysulfide mediator for highly stable Li-S batteries

    KAUST Repository

    Abbas, Syed Ali

    2016-05-24

    The shuttling process involving lithium polysulfides is one of the major factors responsible for the degradation in capacity of lithium–sulfur batteries (LSBs). Herein, we demonstrate a novel and simple strategy—using a bifunctional separator, prepared by spraying poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on pristine separator—to obtain long-cycle LSBs. The negatively charged SO3– groups present in PSS act as an electrostatic shield for soluble lithium polysulfides through mutual coulombic repulsion, whereas PEDOT provides chemical interactions with insoluble polysulfides (Li2S, Li2S2). The dual shielding effect can provide an efficient protection from the shuttling phenomenon by confining lithium polysulfides to the cathode side of the battery. Moreover, coating with PEDOT:PSS transforms the surface of the separator from hydrophobic to hydrophilic, thereby improving the electrochemical performance. We observed an ultralow decay of 0.0364% per cycle when we ran the battery for 1000 cycles at 0.25 C—far superior to that of the pristine separator and one of the lowest recorded values reported at a low current density. We examined the versatility of our separator by preparing a flexible battery that functioned well under various stress conditions; it displayed flawless performance. Accordingly, this economical and simple strategy appears to be an ideal platform for commercialization of LSBs.

  2. Anion and Cation Modulation in Metal Compounds for Bifunctional Overall Water Splitting.

    Science.gov (United States)

    Duan, Jingjing; Chen, Sheng; Vasileff, Anthony; Qiao, Shi Zhang

    2016-09-27

    As substitutes for precious cathodic Pt/C and anodic IrO2 in electrolytic water splitting cells, a bifunctional catalyst electrode (Fe- and O-doped Co2P grown on nickel foam) has been fabricated by manipulating the cations and anions of metal compounds. The modified catalyst electrode exhibits both superior HER and OER performances with high activity, favorable kinetics, and outstanding durability. The overall ability toward water splitting is especially extraordinary, requiring a small overpotential of 333.5 mV to gain a 10 mA cm(-2) current density. A study on the electrocatalytic mechanism reveals that the atomic modulation between cation and anion plays an important role in optimizing the electrocatalytic activity, which greatly expands the active sites in the electrocatalyst. Further, the three-dimensional conductive porous network is highly advantageous for the exposure of active species, the transport of bubble products, and the transfer of electrons and charges, which substantially boosts reaction kinetics and structure stability.

  3. Chromium(VI) removal via reduction-sorption on bi-functional silica adsorbents.

    Science.gov (United States)

    Zaitseva, Nataliya; Zaitsev, Vladimir; Walcarius, Alain

    2013-04-15

    Organically-modified silica gels bearing mercaptopropyl and ethylenediaminetriacetate groups (SiO2-SH/ED3A) have been used for reduction and subsequent sequestration of Cr(VI) species. The uptake mechanism involves Cr(VI) reduction by thiol groups (SH) and further immobilization of the so-generated Cr(III) species via complexation to the ethylenediaminetriacetate moieties (ED3A). The most appropriate pH range (1-3) for complete Cr(VI) reduction-sorption by SiO2-SH/ED3A originates from the balance between full reduction of Cr(VI) by SH, requiring low pH values, and quantitative complexation of Cr(III) by ED3A, which is favored in less acidic media. Such bi-functional adsorbents are considerably more effective at removal of Cr(VI) than those simply modified with thiol groups alone. The whole reduction-sorption process was characterized by fast kinetics, thus permitting efficient use of the SiO2-SH/ED3A adsorbent in dynamic conditions (column experiments). Monitoring the amount of immobilized chromium species on the solid was achieved using X-ray fluorescence spectroscopy and UV-vis spectroscopy. Studying the influence of ionic strength and presence of heavy metals revealed few interference on Cr(VI) removal. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Metal-Organic-Framework-Derived Hybrid Carbon Nanocages as a Bifunctional Electrocatalyst for Oxygen Reduction and Evolution.

    Science.gov (United States)

    Liu, Shaohong; Wang, Zhiyu; Zhou, Si; Yu, Fengjiao; Yu, Mengzhou; Chiang, Chang-Yang; Zhou, Wuzong; Zhao, Jijun; Qiu, Jieshan

    2017-08-01

    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are cornerstone reactions for many renewable energy technologies. Developing cheap yet durable substitutes of precious-metal catalysts, especially the bifunctional electrocatalysts with high activity for both ORR and OER reactions and their streamlined coupling process, are highly desirable to reduce the processing cost and complexity of renewable energy systems. Here, a facile strategy is reported for synthesizing double-shelled hybrid nanocages with outer shells of Co-N-doped graphitic carbon (Co-NGC) and inner shells of N-doped microporous carbon (NC) by templating against core-shell metal-organic frameworks. The double-shelled NC@Co-NGC nanocages well integrate the high activity of Co-NGC shells into the robust NC hollow framework with enhanced diffusion kinetics, exhibiting superior electrocatalytic properties to Pt and RuO2 as a bifunctional electrocatalyst for ORR and OER, and hold a promise as efficient air electrode catalysts in Zn-air batteries. First-principles calculations reveal that the high catalytic activities of Co-NGC shells are due to the synergistic electron transfer and redistribution between the Co nanoparticles, the graphitic carbon, and the doped N species. Strong yet favorable adsorption of an OOH* intermediate on the high density of uncoordinated hollow-site C atoms with respect to the Co lattice in the Co-NGC structure is a vital rate-determining step to achieve excellent bifunctional electrocatalytic activity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Influence of a novel, versatile bifunctional chelator on theranostic properties of a minigastrin analogue.

    Science.gov (United States)

    Pfister, Joachim; Summer, Dominik; Rangger, Christine; Petrik, Milos; von Guggenberg, Elisabeth; Minazzi, Paolo; Giovenzana, Giovanni B; Aloj, Luigi; Decristoforo, Clemens

    2015-12-01

    6-[Bis(carboxymethyl)amino]-1,4-bis(carboxymethyl)-6-methyl-1,4-diazepane (AAZTA ) is a promising chelator with potential advantages over 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) for radiopharmaceutical applications. Its mesocyclic structure enables fast radiolabelling under mild conditions with trivalent metals including not only (68)Ga for positron emission tomography (PET) but also (177)Lu and (111)In for single-photon emission computed tomography (SPECT) and radionuclide therapy. Here, we describe the evaluation of a bifunctional AAZTA derivative conjugated to a model minigastrin derivative as a potential theranostic agent. An AAZTA derivative with an aliphatic C9 chain as linker was coupled to a minigastrin, namely [AAZTA(0), D-Glu(1), desGlu(2-6)]-minigastrin (AAZTA-MG), and labelled with (68)Ga, (177)Lu and (111)In. The characterisation in vitro included stability studies in different media and determination of logD (octanol/PBS). Affinity determination (IC50) and cell uptake studies were performed in A431-CCK2R cells expressing the human CCK2 receptor. μPET/CT and ex vivo biodistribution studies were performed in CCK2 tumour xenograft-bearing nude mice and normal mice. AAZTA-MG showed high radiochemical yields for (68)Ga (>95 %), (177)Lu (>98 %) and (111)In (>98 %). The logD value of -3.7 for both [(68)Ga]- and [(177)Lu]-AAZTA-MG indicates a highly hydrophilic character. Stability tests showed overall high stability in solution with some degradation in human plasma for [(68)Ga]- and transchelation towards DTPA for and [(177)Lu]-AAZTA-MG. An IC50 value of 10.0 nM was determined, which indicates a high affinity for the CCK2 receptor. Specific cell uptake after 60 min was >7.5 % for [(68)Ga]-AAZTA-MG and >9.5 % for [(177)Lu]-AAZTA-MG, comparable to other DOTA-MG-analogues. μPET/CT studies in CCK2 receptor tumour xenografted mice not only revealed high selective accumulation in A431-CCK2R positive tumours of (68)Ga-labelled AAZTA

  6. Ascorbic acid as a bifunctional hydrogen bond donor for the synthesis of cyclic carbonates from CO2 under ambient conditions

    KAUST Repository

    Arayachukiat, Sunatda

    2017-07-14

    Readily available ascorbic acid was discovered as an environmentally benign hydrogen bond donor (HBD) for the synthe-sis of cyclic organic carbonates from CO2 and epoxides in the presence of nucleophilic co-catalysts. The ascorbic acid/TBAI (TBAI: tetrabutylammonium iodide) binary system could be applied for the cycloaddition of CO2 to various epoxides under ambient or mild conditions. DFT calculations and catalysis experiments revealed an intriguing bifunctional mechanism in the step of CO2 insertion involving different hydroxyl moieties (enediol, ethyldiol) of the ascorbic acid scaffold.

  7. A chemically stable europium metal-organic framework for bifunctional chemical sensor and recyclable on-off-on vapor response

    Science.gov (United States)

    Wang, Dongbo; Liu, Jingjuan; Liu, Zhiliang

    2017-07-01

    A ratiometric luminescence sensing method is developed and makes the chemically stable Eu metal-organic framework to be the first bifunctional chemical sensor for Cd2+ and F- ions with naked-eye observation in the field of sensing applications utilizing luminescent Ln-MOFs. This is the first example of luminescent colorimetric sensor caused by the direct dual emissions of a single Ln-MOF. A recyclable vapoluminescent sensor for HCl and NH3 by the naked eye has also been realized.

  8. Radiochemical studies of 99mTc complexes of modified cysteine ligands and bifunctional chelating agents.

    Science.gov (United States)

    Pillai, M R; Kothari, K; Banerjee, S; Samuel, G; Suresh, M; Sarma, H D; Jurisson, S

    1999-07-01

    The synthesis of four novel ligands using the amino-acid cysteine and its ethyl carboxylate derivative is described. The synthetic method involves a two-step procedure, wherein the intermediate Schiff base formed by the condensation of the amino group of the cysteine substrate and salicylaldehyde is reduced to give the target ligands. The intermediates and the final products were characterized by high resolution nuclear magnetic resonance spectroscopy. Complexation studies of the ligands with 99mTc were optimized using stannous tartrate as the reducing agent under varying reaction conditions. The complexes were characterized using standard quality control techniques such as thin layer chromatography, paper electrophoresis, and paper chromatography. Lipophilicities of the complexes were estimated by solvent extraction into chloroform. Substantial changes in net charge and lipophilicity of the 99mTc complexes were observed on substituting the carboxylic acid functionality in ligands I and II with the ethyl carboxylate groups (ligands II and IV). All the ligands formed 99mTc complexes in high yield. Whereas the complexes with ligands I and II were observed to be hydrophilic in nature and not extractable into CHCl3, ligands III and IV resulted in neutral and lipophilic 99mTc complexes. The 99mTc complex with ligand II was not stable and on storage formed a hydrophilic and nonextractable species. The biodistribution of the complexes of ligands I and II showed that they cleared predominantly through the kidneys, whereas the complexes with ligands III and IV were excreted primarily through the hepatobiliary system. No significant brain uptake was observed with the 99mTc complexes with ligands III and IV despite their favorable properties of neutrality, lipophilicity, and conversion into a hydrophilic species. These ligands offer potential for use as bifunctional chelating agents.

  9. Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin-Derived Model Phenolics.

    Science.gov (United States)

    Anderson, Eric; Crisci, Anthony; Murugappan, Karthick; Román-Leshkov, Yuriy

    2017-05-22

    Reductive catalytic fractionation of biomass has recently emerged as a powerful lignin extraction and depolymerization method to produce monomeric aromatic oxygenates in high yields. Here, bifunctional molybdenum-based polyoxometalates supported on titania (POM/TiO2 ) are shown to promote tandem hydrodeoxygenation (HDO) and alkylation reactions, converting lignin-derived oxygenated aromatics into alkylated benzenes and alkylated phenols in high yields. In particular, anisole and 4-propylguaiacol were used as model compounds for this gas-phase study using a packed-bed flow reactor. For anisole, 30 % selectivity for alkylated aromatic compounds (54 % C-alkylation of the methoxy groups by methyl balance) with an overall 72 % selectivity for HDO at 82 % anisole conversion was observed over H3 PMo12 O40 /TiO2 at 7 h on stream. Under similar conditions, 4-propylguaiacol was mainly converted into 4-propylphenol and alkylated 4-propylphenols with a selectivity to alkylated 4-propylphenols of 42 % (77 % C-alkylation) with a total HDO selectivity to 4-propylbenzene and alkylated 4-propylbenzenes of 4 % at 92 % conversion (7 h on stream). Higher catalyst loadings pushed the 4-propylguaiacol conversion to 100 % and resulted in a higher selectivity to propylbenzene of 41 %, alkylated aromatics of 21 % and alkylated phenols of 17 % (51 % C-alkylation). The reactivity studies coupled with catalyst characterization revealed that Lewis acid sites act synergistically with neighboring Brønsted acid sites to simultaneously promote alkylation and hydrodeoxygenation activity. A reaction mechanism is proposed involving activation of the ether bond on a Lewis acid site, followed by methyl transfer and C-alkylation. Mo-based POMs represent a versatile catalytic platform to simultaneously upgrade lignin-derived oxygenated aromatics into alkylated arenes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Novel configuration of bifunctional air electrodes for rechargeable zinc-air batteries

    Science.gov (United States)

    Li, Po-Chieh; Chien, Yu-Ju; Hu, Chi-Chang

    2016-05-01

    A novel configuration of two electrodes containing electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) pressed into a bifunctional air electrode is designed for rechargeable Zn-air batteries. MOC/25BC carbon paper (MOC consisting of α-MnO2 and XC-72 carbon black) and Fe0.1Ni0.9Co2O4/Ti mesh on this air electrode mainly serve as the cathode for the ORR and the anode for the OER, respectively. The morphology and physicochemical properties of Fe0.1Ni0.9Co2O4 are investigated through scanning electron microscopy, inductively coupled plasma-mass spectrometry, and X-ray diffraction. Electrochemical studies comprise linear sweep voltammetry, rotating ring-disk electrode voltammetry, and the full-cell charge-discharge-cycling test. The discharge peak power density of the Zn-air battery with the unique air electrode reaches 88.8 mW cm-2 at 133.6 mA cm-2 and 0.66 V in an alkaline electrolyte under an ambient atmosphere. After 100 charge-discharge cycles at 10 mA cm-2, an increase of 0.3 V between charge and discharge cell voltages is observed. The deep charge-discharge curve (10 h in each step) indicates that the cell voltages of discharge (1.3 V) and charge (1.97 V) remain constant throughout the process. The performance of the proposed rechargeable Zn-air battery is superior to that of most other similar batteries reported in recent studies.

  11. Crystallization, preliminary X-ray crystallographic and cryo-electron microscopy analysis of a bifunctional enzyme fucokinase/L-fucose-1-P-guanylyltransferase from Bacteroides fragilis.

    Science.gov (United States)

    Cheng, Chongyun; Gu, Jianhua; Su, Jing; Ding, Wei; Yin, Jie; Liang, Wenguang; Yu, Xiaoxia; Ma, Jun; Wang, Peng George; Xiao, Zhicheng; Liu, Zhi-Jie

    2014-09-01

    Fucokinase/L-fucose-1-P-guanylyltransferase (FKP) is a bifunctional enzyme which converts L-fucose to Fuc-1-P and thence to GDP-L-fucose through a salvage pathway. The molecular weights of full-length FKP (F-FKP) and C-terminally truncated FKP (C-FKP, residues 300-949) are 105.7 and 71.7 kDa, respectively. In this study, both recombinant F-FKP and C-FKP were expressed and purified. Size-exclusion chromatography experiments and analytical ultracentrifugation results showed that both F-FKP and C-FKP are trimers. Native F-FKP protein was crystallized by the vapour-diffusion method and the crystals belonged to space group P212121 and diffracted synchrotron X-rays to 3.7 Å resolution. The crystal unit-cell parameters are a = 91.36, b = 172.03, c = 358.86 Å, α = β = γ = 90.00°. The three-dimensional features of the F-FKP molecule were observed by cryo-EM (cryo-electron microscopy). The preliminary cryo-EM experiments showed the F-FKP molecules as two parallel disc-shaped objects stacking together. Combining all results together, it is assumed that there are six FKP molecules in one asymmetric unit, which corresponds to a calculated Matthews coefficient of 2.19 Å(3) Da(-1) with 43.83% solvent content. These preliminary crystallographic and cryo-EM microscopy analyses provide basic structural information on FKP.

  12. Standardization of methodology to derivatization and radiolabeling of the anti-CD20 monoclonal antibody from bifunctional chelator DOTA-NHS-Ester

    Energy Technology Data Exchange (ETDEWEB)

    Massicano, Adriana V.F.; Akanji, Akinkunmi G.; Santos, Josefina S.; Pujatti, Priscilla B.; Couto, Renata M.; Massicano, Felipe; Araujo, Elaine Bortoleti de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], E-mail: adriana.avfernandes@gmail.com

    2009-07-01

    Lymphomas are cancers of the lymphatic system, being the most common the non-Hodgkin lymphoma (NHL). The Radioimmunotherapy (RIT), that increase the cytotoxic effect of monoclonal antibodies (mAb), therefore labeling these Mab with different radioisotopes. RIT combines the specificity of the antibody and the toxicity of the radionuclides. The mAb anti-CD20 is used for treatment of relapse or refractory NHL. The labeling of anti- CD20 with {sup 177}Lu, requires a bifunctional chelating agent that is designed to make a 'connect bridge' between the mAb and the radionuclide. The incorporation of the chelating group in mAb structure is called derivatization. The aim of this work is to study the derivatization of anti-CD20 antibody with DOTA-NHS-ester chelating group and labeling parameters to produce {sup 177}Lu-DOTA-Anti CD20. Five milligrams of anti-CD20 were purified by dialysis against phosphate buffer pH 8.0 and derivatized with DOTA-NHS-ester in 1:250, 1:500 and 1:1000 molar ratios. The reaction was conducted for 1 hour in gently mixing at room temperature and remained under refrigeration for 48 hours. The reaction mixture was purified in gel column Sephadex G-50 ; the aliquots that presented greater protein concentration, were mixed and concentrated. The purified antibody conjugated was added to 111-185MBq (3-5mCi) of {sup 177}LuCl3 diluted in 0.4 M acetate buffer pH 5.5. Radiochemical purity was less than 95% in all the molar ratios, indicating necessity of the purification after the labeling. The mAb derivatized showed stable when stored for to 1 month to 4 deg C and 4 days at -20 deg C. (author)

  13. Efficient bifunctional catalyst lipase/organophosphonic acid-functionalized silica for biodiesel synthesis by esterification of oleic acid with ethanol.

    Science.gov (United States)

    Yin, Ping; Chen, Wen; Liu, Wei; Chen, Hou; Qu, Rongjun; Liu, Xiguang; Tang, Qinghua; Xu, Qiang

    2013-07-01

    An efficient bifunctional catalyst lipase/organophosphonic acid-functionalized silica (SG-T-P-LS) has been successfully developed, and biodiesel production of fatty acid ethyl ester (FAEE) from free fatty acid (FFA) oleic acid with short-chain alcohol ethanol catalyzed by SG-T-P-LS was investigated. The process optimization using response surface methodology (RSM) was performed and the interactions between the operational variables were elucidated, and it was found that the molar ratio of alcohol to acid was the most significant factor. The optimum values for maximum conversion ratio can be obtained by using a Box-Behnken center-united design, and the conversion ratio could reach 89.94 ± 0.42% under the conditions that ethanol/acid molar ratio was 1.05:1 and SG-T-P-LS to FFA weight ratio was 14.9 wt.% at 28.6°C. The research results show that SG-T-P and LS-20 could work cooperatively to promote the esterification reaction, and the bifunctional catalyst SG-T-P-LS is a potential catalyst for biodiesel production. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. A field trial of novel bifunctional resins for removing pertechnetate (TcO{sub 4}{sup {minus}}) from contaminated groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Gu, B.; Liang, L.; Brown, G.M.; Bonnesen, P.V.; Moyer, B.A. [Oak Ridge National Lab., TN (United States); Alexandratos, S.D.; Ober, R. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry

    1998-03-01

    A field trial using a custom-designed bifunctional synthetic resin prepared at the University of Tennessee and designed to selectively remove pertechnetate (TcO{sub 4}{sup {minus}}) from groundwater was conducted in summer 1997 at the Northwest Plume Pump-and-Treat Facility at the US Department of Energy`s Paducah Gaseous Diffusion Plant (PGDP) site. The bifunctional resin, RO-02-119, was a copolymer of vinylbenzylchloride and divinylbenzene that had been functionalized with trihexylamine and triethylamine. The experiment was a parallel test of the synthetic resin and a commercial resin, Purolite A-520E, to directly compare the performance of the two resins. Purolite resin is currently used by the treatment facility to remove Tc-99 from the contaminated groundwater containing {approximately}1,000 pCi/L TcO{sub 4}{sup {minus}}. A total of {approximately}692,000 bed volumes of groundwater was passed through the column containing the synthetic resin (RO-02-119) whereas only {approximately}205,000 bed volumes of groundwater were passed through the Purolite resin column because of reduced hydraulic conductivity and clogging within the latter column. Despite less groundwater passing through the Purolite resin column, however, the breakthrough of TcO{sub 4}{sup {minus}} occurred earlier in the Purolite column than in the RO-02-119 column.

  15. MOF-Derived Ultrathin Cobalt Phosphide Nanosheets as Efficient Bifunctional Hydrogen Evolution Reaction and Oxygen Evolution Reaction Electrocatalysts

    Directory of Open Access Journals (Sweden)

    Hong Li

    2018-02-01

    Full Text Available The development of a highly efficient and stable bifunctional electrocatalyst for water splitting is still a challenging issue in obtaining clean and sustainable chemical fuels. Herein, a novel bifunctional catalyst consisting of 2D transition-metal phosphide nanosheets with abundant reactive sites templated by Co-centered metal−organic framework nanosheets, denoted as CoP-NS/C, has been developed through a facile one-step low-temperature phosphidation process. The as-prepared CoP-NS/C has large specific surface area and ultrathin nanosheets morphology providing rich catalytic active sites. It shows excellent electrocatalytic performances for hydrogen evolution reaction (HER and oxygen evolution reaction (OER in acidic and alkaline media, with the Tafel slopes of 59 and 64 mV/dec and a current density of 10 mA/cm2 at the overpotentials of 140 and 292 mV, respectively, which are remarkably superior to those of CoP/C, CoP particles, and comparable to those of commercial noble-metal catalysts. In addition, the CoP-NS/C also shows good durability after a long-term test.

  16. A novel bifunctional Ni-doped TiO2 inverse opal with enhanced SERS performance and excellent photocatalytic activity

    Science.gov (United States)

    Li, Xuehong; Wu, Yun; Shen, Yuhua; Sun, Yan; Yang, Ying; Xie, Anjian

    2018-01-01

    Three-dimensional inverse opal photonic microarray (IOPM) structure exhibits good qualities in structural regularity and interconnectivity, such as high specific surface area, large pore volume, uniform pore size, and ordered periodic construction. Here, a novel nickel-doped titanium dioxide IOPM (Ni-TiO2 IOPM) was fabricated for the first time as a bifunctional material for the applications of surface-enhanced Raman scattering (SERS) substrate and photocatalyst. The Ni doping could change the defect concentration of the substrate to enhance the SERS effect, and could increase the light absorption of the substrate in visible region. The synergistic effect of Ni doping and the periodically ordered porous structure enhanced both SERS sensitivity and photocatalytic activity. As a SERS substrate, the Ni-TiO2 IOPM exhibited highly sensitive detection capability for 4-mercaptobenzoic acid (4-MBA) at a concentration as low as 1 × 10-11 M. Under simulated sunlight, about 95% of the methylene blue (MB) was degraded within 90 min when Ni-TiO2 IOPM was used as the photocatalytst. The Ni-TiO2 IOPM prepared in this work may be a promising bifunctional SERS substrate candidate for organic sewage detection and environment protection. In addition, the fabrication strategy can be extended to synthesize other nanomaterials with orderly and porous structure.

  17. Bifunctional carbohydrate biopolymers entrapped lipase as catalyst for the two consecutive conversions of α-pinene to oxy-derivatives.

    Science.gov (United States)

    Tudorache, Madalina; Gheorghe, Andreea; Negoi, Alina; Enache, Madalin; Maria, Gabriel-Mihai; Parvulescu, Vasile I

    2016-11-05

    Bifunctional catalysts designed as carbohydrate biopolymers entrapping lipase have been investigated for the biotransformation of a natural compound (α-pinene) to oxy-derivatives. Lipases assisted the epoxidation of α-pinene using H2O2 as oxidation reagent and ethyl acetate as both acetate-supplier and solvent affording α-pinene oxide as the main product. Further, the biopolymer promoted the isomerization of α-pinene oxide to campholenic aldehyde and trans-carenol. In this case, the biopolymers played double roles of the support and also active part of the bifunctional catalyst. Screening of enzymes and their entrapping in a biopolymeric matrix (e.g. Ca-alginate and κ-carrageenan) indicated the lipase extracted from Aspergillus niger as the most efficient. In addition, the presence of biopolymers enhanced the catalytic activity of the immobilized lipase (i.e. 13.39×10(3), 19.76×10(3)and 26.46×10(3) for the free lipase, lipase-carrageenan and lipase-alginate, respectively). The catalysts stability and reusability were confirmed in eight consecutively reaction runs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Preparation of highly hydrophobic cotton fabrics by modification with bifunctional silsesquioxanes in the sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Przybylak, Marcin, E-mail: marcin.przybylak@ppnt.poznan.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland); Maciejewski, Hieronim, E-mail: maciejm@amu.edu.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland); Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań (Poland); Dutkiewicz, Agnieszka, E-mail: agdut@interia.pl [Poznań Science and Technology Park, Adam Mickiewicz University Foundation, Rubież 46, 61-612 Poznań (Poland)

    2016-11-30

    Highlights: • Fabric hydrophobization process using bifunctional silsesquioxanes was studied. • Superhydrophobic fabric was produced using fluorofunctional silsesquioxanes. • Surface of modified fabrics was analyzed using different techniques. - Abstract: The surface modification of cotton fabrics was carried out using two types of bifunctional fluorinated silsesquioxanes with different ratios of functional groups. The modification was performed either by one- or two-step process. Two methods, the sol-gel and the dip coating method were used in different configurations. The heat treatment and the washing process were applied after modification. The wettability of cotton fabric was evaluated by measuring water contact angles (WCA). Changes in the surface morphology were examined by scanning electron microscopy (SEM, SEM-LFD) and atomic force microscopy (AFM). Moreover, the modified fabrics were subjected to analysis of elemental composition of the applied coatings using SEM-EDS techniques. Highly hydrophobic textiles were obtained in all cases studied and one of the modifications resulted in imparting superhydrophobic properties. Most of impregnated textiles remained hydrophobic even after multiple washing process which shows that the studied modification is durable.

  19. Reshaping Lithium Plating/Stripping Behavior via Bifunctional Polymer Electrolyte for Room-Temperature Solid Li Metal Batteries.

    Science.gov (United States)

    Zeng, Xian-Xiang; Yin, Ya-Xia; Li, Nian-Wu; Du, Wen-Cheng; Guo, Yu-Guo; Wan, Li-Jun

    2016-12-14

    High-energy rechargeable Li metal batteries are hindered by dendrite growth due to the use of a liquid electrolyte. Solid polymer electrolytes, as promising candidates to solve the above issue, are expected to own high Li ion conductivity without sacrificing mechanical strength, which is still a big challenge to realize. In this study, a bifunctional solid polymer electrolyte exactly having these two merits is proposed with an interpenetrating network of poly(ether-acrylate) (ipn-PEA) and realized via photopolymerization of ion-conductive poly(ethylene oxide) and branched acrylate. The ipn-PEA electrolyte with facile processing capability integrates high mechanical strength (ca. 12 GPa) with high room-temperature ionic conductance (0.22 mS cm-1), and significantly promotes uniform Li plating/stripping. Li metal full cells assembled with ipn-PEA electrolyte and cathodes within 4.5 V vs Li+/Li operate effectively at a rate of 5 C and cycle stably at a rate of 1 C at room temperature. Because of its fabrication simplicity and compelling characteristics, the bifunctional ipn-PEA electrolyte reshapes the feasibility of room-temperature solid-state Li metal batteries.

  20. "Bis-Click" Ligation of DNA: Template-Controlled Assembly, Circularisation and Functionalisation with Bifunctional and Trifunctional Azides.

    Science.gov (United States)

    Yang, Haozhe; Seela, Frank

    2017-03-08

    Ligation and circularisation of oligonucleotides containing terminal triple bonds was performed with bifunctional or trifunctional azides. Both reactions are high yielding. Template-assisted bis-click ligation of two individual non-complementary oligonucleotide strands was accomplished to yield heterodimers exclusively. In this context, the template fulfils two functions: it accelerates the ligation reaction and controls product assembly (heterodimer vs. homodimer formation). Intermolecular bis-click circularisation of one oligonucleotide strand took place without template assistance. For construction of oligonucleotides with terminal triple bonds in the nucleobase side chain, 7- or 5-functionalised 7-deaza-dA and dU residues were used. These oligonucleotides are directly accessible by solid-phase synthesis. When trifunctional azides were employed instead of bifunctional linkers, functionalisation of the remaining azido group was performed with small molecules such as 1-ethynyl pyrene, biotin propargyl amide or with ethynylated oligonucleotides. By this means, branched DNA was constructed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Steam reforming of acetic acid as a biomass derived oxygenate: Bifunctional pathway for hydrogen formation over Pt/ZrO2 catalysts.

    NARCIS (Netherlands)

    Takanabe, K.; Aika, Ken-ichi; Inazu, Koji; Baba, Toshihide; Seshan, Kulathuiyer; Lefferts, Leonardus

    2006-01-01

    Mechanistic studies on steam reforming of acetic acid over Pt/ZrO2 catalysts were performed as extension of our previous work [K. Takanabe, K. Aika, K. Seshan, L. Lefferts, J. Catal. 227 (2004) 101]. An overall picture of the bifunctional mechanism is established for steam reforming of acetic acid,

  2. Identifying active surface phases for metal oxide electrocatalysts: a study of manganese oxide bi-functional catalysts for oxygen reduction and water oxidation catalysis

    DEFF Research Database (Denmark)

    Su, Hai-Yan; Gorlin, Yelena; Man, Isabela Costinela

    2012-01-01

    Progress in the field of electrocatalysis is often hampered by the difficulty in identifying the active site on an electrode surface. Herein we combine theoretical analysis and electrochemical methods to identify the active surfaces in a manganese oxide bi-functional catalyst for the oxygen reduc...

  3. Multicolor imaging and the anticancer effect of a bifunctional silica nanosystem based on the complex of graphene quantum dots and hypocrellin A.

    Science.gov (United States)

    Zhou, Lin; Zhou, Lin; Ge, Xuefeng; Zhou, Jiahong; Wei, Shaohua; Shen, Jian

    2015-01-01

    An effective theranostic platform based on porous silica nanoparticles encapsulated with the complex of a photodynamic anticancer drug and graphene quantum dots (GQDs), with the bifunction of multicolor imaging and satisfactory photo-induced anticancer activity, was successfully designed and prepared for in vitro photodynamic therapy (PDT) of superficial cancer.

  4. Promotion of Ca-Co Bifunctional Catalyst/Sorbent with Yttrium for Hydrogen Production in Modified Chemical Looping Steam Methane Reforming Process

    Directory of Open Access Journals (Sweden)

    Samira Akbari-Emadabadi

    2017-09-01

    Full Text Available In this study, the application of a calcium-based bifunctional catalyst/sorbent is investigated in modified chemical looping steam methane reforming (CLSMR process for in situ CO2 sorption and H2 production. The yttrium promoted Ca-Co samples were synthesized and applied as bifunctional catalysts/sorbent. The influence of reduction temperature (500–750 °C, Ca/Co and Ca/Y ratios (1.5–∞ and 3–18, respectively and catalyst life time are determined in CLSMR process. The physicochemical transformation of fresh, used and regenerated samples after 16 redox cycles are determined using X-ray powder diffraction (XRD, N2 adsorption–desorption, field emission scanning electron microscopy (FESEM, energy dispersive X-ray spectroscopy (EDX and transmission electron microscopy (TEM techniques. The effect of yttrium promoter on the structure of catalyst and regeneration step on the reversibility of bifunctional catalyst/sorbent was two important factors. The characterization results revealed that the presence of yttrium in the structure of Ca-9Co sample could improve the morphology and textural properties of catalyst/sorbents. The suitable reversibility of bifunctional catalyst/sorbents during the repeated cycles is confirmed by characterization of calcined samples. The Ca-9Co-4.5Y as optimal catalyst illustrated superior performance and stability. It showed about 95.8% methane conversion and 82.9% hydrogen yield at 700 °C and stable activity during 16 redox cycles.

  5. Effects of thiourea and ammonium bicarbonate on the formation and stability of bifunctional cisplatin-DNA adducts : consequences for the accurate quantification of adducts in (cellular) DNA

    NARCIS (Netherlands)

    Fichtinger-Schepman, A.M.J.; Dijk-Knijnenburg, H.C.M. van; Dijt, F.J.; Velde-Visser, S.D. van der; Berends, F.; Baan, R.A.

    1995-01-01

    Cisplatin reacts with DNA by forming mainly bifunctional adducts via reactive monofunctional intermediates. When freshly platinated DNA was postincubated with thiourea (10 mM, at 23 or 37°C) for periods of up to 24 h, followed by determination of mono- and diadducts, a rapid initial decrease was

  6. Electrospinning preparation and properties of magnetic-photoluminescent bifunctional bistrand-aligned composite nanofibers bundles

    Science.gov (United States)

    Gai, Guangqing; Wang, Liyan; Dong, Xiangting; Zheng, Chunmei; Yu, Wensheng; Wang, Jinxian; Xiao, Xinfu

    2013-04-01

    Fe3O4/PVP//Eu(BA)3phen/PVP magnetic-photoluminescent bifunctional bistrand-aligned composite nanofibers bundles based on ferroferric oxide(Fe3O4) nanoparticles and europium complex Eu(BA)3phen (BA = benzoic acid) were fabricated via electrospinning by employing a homemade parallel axial electrospinning setup with the side by side dual spinnerets for the first time. The structures, morphology, and properties of the as-prepared products were investigated in detail by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy (TEM), a fluorescence spectrometer, and a vibrating sample magnetometer. SEM analysis showed the average diameter of the individual-strand fiber of the bistrand-aligned composite nanofibers bundles was 200 ± 25 nm. TEM image demonstrated that Fe3O4 nanoparticles were only dispersed into one strand of the bistrand-aligned composite nanofibers bundles, and the average diameter of Fe3O4 nanoparticles was about 15 nm. Under the excitation of 274 nm ultraviolet light, Fe3O4/PVP//Eu(BA)3phen/PVP bistrand-aligned composite nanofibers bundles exhibited red emissions of predominant peaks at 592 and 616 nm, which were respectively attributed to the 5D0 → 7F1 and 5D0 → 7F2 transitions of Eu3+ ions. The fluorescence intensity of the bistrand-aligned composite nanofibers bundles was higher than that of Fe3O4/Eu(BA)3phen/PVP composite nanofibers, and was decreased with the increase of the amounts of Fe3O4 nanoparticles. The saturation magnetizations of the bistrand-aligned composite nanofibers bundles and the Fe3O4/Eu(BA)3phen/PVP composite nanofibers were about equal when the two nanostructures contained the same mass ratios of Fe3O4 nanoparticles, but the saturation magnetizations of the bistrand-aligned composite nanofibers bundles were increased with the increase of the amounts of Fe3O4 nanoparticles. The new type Fe3O4/PVP//Eu(BA)3phen/PVP bistrand-aligned composite nanofibers

  7. Thrombolytic, anticoagulant and antiplatelet activities of codiase, a bi-functional fibrinolytic enzyme from Codium fragile.

    Science.gov (United States)

    Choi, Jun-Hui; Sapkota, Kumar; Park, Se-Eun; Kim, Seung; Kim, Sung-Jun

    2013-06-01

    Thrombosis is a leading cause of morbidity and mortality throughout the world. Thrombolytic agents are important for both the prevention and treatment of thrombosis. In this study, codiase, a new bi-functional fibrinolytic serine protease having thrombolytic, anticoagulant, and antiplatelet activities was purified from marine green alga, Codium fragile. The molecular weight of the enzyme was estimated to be 48.9 kDa by SDS-PAGE, and mass spectrometry. Fibrin zymography analysis showed an active band with similar molecular weight. The N-terminal sequence was found to be APKASTDQTLPL, which is different from that of other known fibrinolytic enzymes. Codiase displayed maximum activity at 30 °C and pH 6.0, and the activity was inhibited by Zn(2+) and Fe(2+). Moreover, the enzyme activity was strongly inhibited by serine protease inhibitor such as PMSF. Codiase exhibited high specificity for the substrate S-2288, and the Km and Vmax values for this substrate were found to be 0.24 mM and 79 U/ml respectively. Fibrin plate assays revealed that it was able to hydrolyze fibrin clot either directly or by activation of plasminogen. Codiase effectively hydrolyzed fibrin and fibrinogen, preferentially degrading α- and Aα chains, followed by γ-γ, and γ-chains. However, it provoked slower degradation of Bβ and β-chains. The structural change of fibrin clot and fibrinogen by codiase was also detected by FTIR-ATR spectroscopy analysis. In vitro and in vivo studies revealed that codiase reduces thrombosis in concentration-dependent manner. Codiase was found to prolong activated partial thromboplastin time (APTT), and prothrombin time (PT). PFA-100 studies showed that codiase prolonged the closure time (CT) of citrated whole human blood. These favorable antithrombotic profiles together with its anticoagulant and platelet disaggregation properties, and lack of toxicity to mice and NIH-3T3 cells, make it a potential agent for thrombolytic therapy. Copyright © 2013 Elsevier

  8. Parameter design and experimental study of a bifunctional isolator for optical payload protection and stabilization

    Science.gov (United States)

    Wang, Guang-yuan; Guan, Xin; Cao, Dong-jing; Tang, Shao-fan; Chen, Xiang; Liang, Lu; Zheng, Gang-tie

    2017-11-01

    With the raise of resolution, optical payloads are becoming increasingly sensitive to satellite jitter. An approach where the entire spacecraft is pointed with great accuracy requires sophisticated and expensive bus design. In an effort to lower the overall cost of space missions that require highly stable line-of-sight pointing, a method of separating the bus and the payload with low frequency isolators is proposed. This isolation system can block the transmission of disturbance and allow relatively large bus motion. However, if the isolator is linear then there is a trade-off between isolation and static deflection as the launch and the on-orbit stage have difference requirements on the isolation frequency. Otherwise, an extra locking system should be appended to protect the payload before getting into orbit, as the STABLE isolation system[1] and the MIM isolation system[2] did. To overcome this limitation, an alternative approach is to design a nonlinear isolator with high-static stiffness during launch and low dynamic stiffness on orbit. Several specially designed nonlinear isolators have achieved low dynamic stiffness with large static load capacity. Virgin[3] considered a structure made from a highly deformed elastic element to achieve a softening spring. Platus[4] exploited the buckling of beams under axial load in a specific configuration to achieve a negative stiffness in combination with a positive stiffness, and hence low-dynamic stiffness. Others have achieved the same by connecting linear springs with positive stiffness in parallel with elements of negative stiffness[5] [7]. In the present study, a bifunctional isolator has been developed for optical payloads. The isolator have good performance both during launch and on orbit because of its specially designed nonlinear stiffness and damping. The isolator works in a linear part with low stiffness and small damping ratio under the micro-vibration and microgravity on orbit. The transmissibility

  9. Synthesis of bifunctional molecules containing [12]aneN3 and coumarin moieties as effective DNA condensation agents and new non-viral gene vectors.

    Science.gov (United States)

    Yue, Pan; Zhang, Ying; Guo, Zhi-Fo; Cao, Ao-Cheng; Lu, Zhong-Lin; Zhai, Yong-Gong

    2015-04-21

    A series of bifunctional molecules with different combinations of macrocyclic polyamine [12]aneN3 and coumarin moieties, 4a/b and 5a/b, were synthesized by a two-step copper(I)-mediated alkyne–azide click reactions between 1,3,5-tris(azidomethyl)benzene and Boc-protected N-propynyl-[12]aneN3/7-propynyloxycoumarins. Agarose gel electrophoresis experiments indicated that bifunctional molecules 4b and 5b effectively induced complete plasmid DNA condensation at concentrations up to 40 μM. It was found that the structural variation had a major impact on the condensation behavior of these compounds. The electrostatic interaction involving the [12]aneN3 moiety can be compensated by the binding contribution of the coumarin units during the DNA condensation process. These two types of interaction showed different effects on the reversibility of DNA condensation. Results from studies using dynamic laser scattering, atomic force microscopy, and EB replacement assay further supported the above conclusion. Cytotoxicity assays on bifunctional compounds 4a/b and 5a/b indicated their low cytotoxicity. Results from cellular uptake and cell transfection experiments proved that bifunctional compounds 4b and 5b successfully served as non-viral gene vectors. Furthermore, methyl substituents attached to the coumarin unit (4b and 5b) greatly enhanced their DNA condensation capability and gene transfection. These bifunctional molecules, with the advantages of lower cytotoxicity, good water solubility, and potential structural modification, will have great potential for the development of new non-viral gene delivery agents.

  10. Acid/base bifunctional carbonaceous nanomaterial with large surface area: Preparation, characterization, and adsorption properties for cationic and anionic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kai; Ma, Chun–Fang; Ling, Yuan; Li, Meng [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Gao, Qiang, E-mail: gaoqiang@cug.edu.cn [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Engineering Research Center of Nano-Geo Materials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Luo, Wen–Jun, E-mail: heartnohome@yahoo.com.cn [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China)

    2015-07-15

    Nanostructured carbonaceous materials are extremely important in the nano field, yet developing simple, mild, and “green” methods that can make such materials possess large surface area and rich functional groups on their surfaces still remains a considerable challenge. Herein, a one-pot and environment-friendly method, i.e., thermal treatment (180 °C; 18 h) of water mixed with glucose and chitosan (CTS), has been proposed. The resultant carbonaceous nanomaterials were characterized by field emitting scanning electron microscope, N{sub 2} adsorption/desorption, Fourier transform infrared spectroscope, X-ray photoelectron spectroscopy, and zeta-potential analysis. It was found that, in contrast to the conventional hydrothermally carbonized product from pure glucose, with low surface area (9.3 m{sup 2} g{sup −1}) and pore volume (0.016 cm{sup 3} g{sup −1}), the CTS-added carbonaceous products showed satisfactory textural parameters (surface area and pore volume up to 254 m{sup 2} g{sup −1} and 0.701 cm{sup 3} g{sup −1}, respectively). Moreover, it was also interestingly found that these CTS-added carbonaceous products possessed both acidic (–COOH) and basic (–NH{sub 2}) groups on their surfaces. Taking the advantages of large surface area and –COOH/–NH{sub 2} bifunctional surface, the carbonaceous nanomaterials exhibited excellent performance for adsorptions of cationic compound (i.e., methylene blue) at pH 10 and anionic compound (i.e., acid red 18) at pH 2, respectively. This work not only provides a simple and green route to prepare acid/base bifunctional carbonaceous nanomaterials with large surface area but also well demonstrates their potential for application in adsorption. - Highlights: • A simple and green method was proposed to prepare carbon nanomaterials. • The carbon product showed acid/base bifunctional surface with large surface area. • The carbon material could efficiently adsorb both cationic and anionic compounds.

  11. Two-stage gene assembly/cloning of a member of the TspDTI subfamily of bifunctional restriction endonucleases, TthHB27I.

    Science.gov (United States)

    Krefft, Daria; Zylicz-Stachula, Agnieszka; Mulkiewicz, Ewa; Papkov, Aliaksei; Jezewska-Frackowiak, Joanna; Skowron, Piotr M

    2015-01-20

    The Thermus sp. family of bifunctional type IIS/IIG/IIC restriction endonucleases (REase)-methyltransferases (MTase) comprises thermo-stable TaqII, TspGWI, TspDTI, TsoI, Tth111II/TthHB27I enzymes as well as a number of putative enzymes/open reading frames (ORFs). All of the family members share properties including a large protein size (ca. 120kDa), amino acid (aa) sequence homologies, enzymatic activity modulation by S-adenosylmethionine (SAM), recognition of similar asymmetric cognate DNA sites and cleavage at a distance of 11/9 nt. Analysis of the enzyme aa sequences and domain/motif organisation led to further Thermus sp. family division into the TspDTI and TspGWI subfamilies. The latter exhibits an unprecedented phenomenon of DNA recognition change upon substitution of SAM by its analogue, sinefungin (SIN), towards a very frequent DNA cleavage. We report cloning in Escherichia coli (E. coli), using a two-stage procedure and a putative tthHB27IRM gene, detected by bioinformatics analysis of the Thermus thermophilus HB27 (T. thermophilus) genome. The functionality of a 3366 base pair (bp)-/1121 aa-long, high GC content ORF was validated experimentally through the expression in E. coli. Protein features corroborated with the reclassification of TthHB27I into the TspDTI subfamily, which manifested in terms of aa-sequence/motif homologies and insensitivity to SIN-induced specificity shift. However, both SAM and SIN stimulated the REase DNA cleavage activity by at least 16-32 times; the highest was observed for the Thermus sp. family. The availability of TthHB27I and the need to include SAM or SIN in the reaction in order to convert the enzyme from "hibernation" status to efficient DNA cleavage is of practical significance in molecular biotechnology, extending the palette of available REase specificities. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase: head-to-head with a bifunctional enzyme that controls glycolysis.

    Science.gov (United States)

    Rider, Mark H; Bertrand, Luc; Vertommen, Didier; Michels, Paul A; Rousseau, Guy G; Hue, Louis

    2004-08-01

    Fru-2,6-P2 (fructose 2,6-bisphosphate) is a signal molecule that controls glycolysis. Since its discovery more than 20 years ago, inroads have been made towards the understanding of the structure-function relationships in PFK-2 (6-phosphofructo-2-kinase)/FBPase-2 (fructose-2,6-bisphosphatase), the homodimeric bifunctional enzyme that catalyses the synthesis and degradation of Fru-2,6-P2. The FBPase-2 domain of the enzyme subunit bears sequence, mechanistic and structural similarity to the histidine phosphatase family of enzymes. The PFK-2 domain was originally thought to resemble bacterial PFK-1 (6-phosphofructo-1-kinase), but this proved not to be correct. Molecular modelling of the PFK-2 domain revealed that, instead, it has the same fold as adenylate kinase. This was confirmed by X-ray crystallography. A PFK-2/FBPase-2 sequence in the genome of one prokaryote, the proteobacterium Desulfovibrio desulfuricans, could be the result of horizontal gene transfer from a eukaryote distantly related to all other organisms, possibly a protist. This, together with the presence of PFK-2/FBPase-2 genes in trypanosomatids (albeit with possibly only one of the domains active), indicates that fusion of genes initially coding for separate PFK-2 and FBPase-2 domains might have occurred early in evolution. In the enzyme homodimer, the PFK-2 domains come together in a head-to-head like fashion, whereas the FBPase-2 domains can function as monomers. There are four PFK-2/FBPase-2 isoenzymes in mammals, each coded by a different gene that expresses several isoforms of each isoenzyme. In these genes, regulatory sequences have been identified which account for their long-term control by hormones and tissue-specific transcription factors. One of these, HNF-6 (hepatocyte nuclear factor-6), was discovered in this way. As to short-term control, the liver isoenzyme is phosphorylated at the N-terminus, adjacent to the PFK-2 domain, by PKA (cAMP-dependent protein kinase), leading to PFK-2

  13. Real-time NMR monitoring of intermediates and labile products of the bifunctional enzyme UDP-apiose/UDP-xylose synthase.

    Science.gov (United States)

    Guyett, Paul; Glushka, John; Gu, Xiaogang; Bar-Peled, Maor

    2009-06-12

    The conversion of UDP-alpha-d-glucuronic acid to UDP-alpha-d-xylose and UDP-alpha-d-apiose by a bifunctional potato enzyme UDP-apiose/UDP-xylose synthase was studied using real-time nuclear magnetic resonance (NMR) spectroscopy. UDP-alpha-d-glucuronic acid is converted via the intermediate uridine 5'-beta-l-threo-pentapyranosyl-4''-ulose diphosphate to UDP-alpha-d-apiose and simultaneously to UDP-alpha-d-xylose. The UDP-alpha-d-apiose that is formed is unstable and is converted to alpha-d-apio-furanosyl-1,2-cyclic phosphate and UMP. High-resolution real-time NMR spectroscopy is a powerful tool for the direct and quantitative characterization of previously undetected transient and labile components formed during a complex enzyme-catalyzed reaction.

  14. Functional Analyses of Oxygenases in Jadomycin Biosynthesis and Identification of JadH as a Bifunctional Oxygenase/Dehydrase*

    Science.gov (United States)

    Chen, Yi-Hua; Wang, Chen-Chen; Greenwell, Lisa; Rix, Uwe; Hoffmeister, Dirk; Vining, Leo C.; Rohr, Jürgen; Yang, Ke-Qian

    2010-01-01

    A novel angucycline metabolite, 2,3-dehydro-UWM6, was identified in a jadH mutant of Streptomyces venezuelae ISP5230. Both UWM6 and 2,3-dehydro-UWM6 could be converted to jadomycin A or B by a ketosynthase a (jadA) mutant of S. venezuelae. These angucycline intermediates were also converted to jadomycin A by transformant of the heterologous host Streptomyces lividans expressing the jadFGH oxygenases in vivo and by its cell-free extracts in vitro; thus the three gene products JadFGH are implicated in catalysis of the post-polyketide synthase biosynthetic reactions converting UWM6 to jadomycin aglycone. Genetic and biochemical analyses indicate that JadH possesses dehydrase activity, not previously associated with polyketide-modifying oxygenase. Since the formation of aromatic polyketides often requires multiple dehydration steps, bifunctionality of oxygenases modifying aromatic polyketides may be a general phenomenon. PMID:15817470

  15. Controllable growth of semiconductor heterostructures mediated by bifunctional Ag2S nanocrystals as catalyst or source-host.

    Science.gov (United States)

    Zhu, Guoxing; Xu, Zheng

    2011-01-12

    We demonstrate that Ag(2)S nanocrystals are the bifunctional mediator for controllable growth of semiconductor heterostructures including more complicated multisegments heterostructures in solution-phase, which is a new type of nanomediator and quite different from the metal nanoparticle catalyst. The intrinsic high Ag(+) ion mobility makes Ag(2)S nanocrystals not only exhibit excellent catalytic function for growth of metal sulfide heterostructures but also act as a source-host for growth of ternary semiconductor heterostructures, for example, Ag(2)S-AgInS(2). The semiconductors grow epitaxially from or inward in Ag(2)S nanocrystals forming single-crystalline heterostructures. Moreover, the method developed here also can construct multisegments heterostructures, for example, Ag(2)S-CdS-ZnS, AgInS(2)-Ag(2)S-AgInS(2). The interfacial structure is still stable even if the lattice mismatch is quite large, which is a unique feature of this method.

  16. Realization of bifunction: dual-band absorption and broad band polarization conversion by zigzag birefringent reflective metamaterial

    Science.gov (United States)

    Chen, Jiao; Yang, Helin; Zhang, Guoping; Yu, Zetai; Huang, Xiaojun; Hu, Sen

    2017-05-01

    In this paper, we propose and fabricate a kind of zigzag birefringent reflective metamaterial, the surface of which is a 1D rough surface. It can realize both multiple absorption and broadband polarization conversion at different frequency ranges of microwave. This metamaterial is made of a ring-shaped metal piece that is deposited on one side of a piece of grounded zigzag dielectric substrate. The absorptivities are 99.4% and 97.3% at 3.32 and 6.87 GHz respectively, and the polarization conversion ratio is more than 90% from 8.43 to 11.55 GHz, when the incident wave illuminates the sample with different polarization angles. A bifunctional device based on this metamaterial can act as either an absorber or a polarizer. This work is of significance to study the electromagnetic properties of rough surface metamaterials and provides an encouraging example in metamaterial design for combining different functions into one device.

  17. Identification and Overexpression of a Bifunctional Aldehyde/Alcohol Dehydrogenase Responsible for Ethanol Production in Thermoanaerobacter mathranii

    DEFF Research Database (Denmark)

    Yao, Shuo; Just Mikkelsen, Marie

    2010-01-01

    B), butanol dehydrogenase (BdhA) and NAD(H)-dependent bifunctional aldehyde/alcohol dehydrogenase (AdhE), respectively. Here we observed that AdhE is an important enzyme responsible for ethanol production in T. mathranii based on the constructed adh knockout strains. An adhE knockout strain fails to produce...... ethanol as a fermentation product, while other adh knockout strains showed no significant difference from the wild type. Further analysis revealed that the ΔadhE strain was defective in aldehyde dehydrogenase activity, but still maintained alcohol dehydrogenase activity. This showed that AdhE is the major....... Overexpressions of AdhE in strain BG1E1 with xylose as a substrate facilitate the production of ethanol at an increased yield. Copyright © 2010 S. Karger AG, Basel...

  18. Graphene-cobaltite-Pd hybrid materials for use as efficient bifunctional electrocatalysts in alkaline direct methanol fuel cells.

    Science.gov (United States)

    Sharma, Chandra Shekhar; Awasthi, Rahul; Singh, Ravindra Nath; Sinha, Akhoury Sudhir Kumar

    2013-12-14

    Hybrid materials comprising of Pd, MCo2O4 (where M = Mn, Co or Ni) and graphene have been prepared for use as efficient bifunctional electrocatalysts in alkaline direct methanol fuel cells. Structural and electrochemical characterizations were carried out using X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, chronoamperometry and cyclic, CO stripping, and linear sweep voltammetries. The study revealed that all the three hybrid materials are active for both methanol oxidation (MOR) and oxygen reduction (ORR) reactions in 1 M KOH. However, the Pd-MnCo2O4/GNS hybrid electrode exhibited the greatest MOR and ORR activities. This active hybrid electrode has also outstanding stability under both MOR and ORR conditions, while Pt- and other Pd-based catalysts undergo degradation under similar experimental conditions. The Pd-MnCo2O4/GNS hybrid catalyst exhibited superior ORR activity and stability compared to even Pt in alkaline solutions.

  19. Opportunities and challenges in the electrocatalysis of CO2 and CO reduction using bifunctional surfaces

    DEFF Research Database (Denmark)

    Jovanov, Zarko; Hansen, Heine A.; Varela Gasque, Ana Sofia

    2016-01-01

    "bifunctional" catalysts using Au-Cd based alloys inspired by theoretical modelling. Density functional theory calculations suggest more favourable thermodynamics for CO2 reduction to CO and methanol on mixed Au-Cd sites on Au3Cd relative to similar values on Au. We use various tools to test the bulk......Electrolysis could enable the large-scale conversion of CO2 to fuels and small molecules. This perspective discusses the state-of-the-art understanding of CO2 and CO reduction electrocatalysis and provides an overview of the most promising approaches undertaken thus far. We set to explore....... The catalytic performance is most consistent with Au-terminated step surface on a bulk alloy, possibly formed through adsorbate-induced restructuring. We highlight that future bimetallic catalysts must consider potential-dependent surface restructuring effects caused by reaction intermediates....

  20. Nb-Based Zeolites: Efficient bi-Functional Catalysts for the One-Pot Synthesis of Succinic Acid from Glucose

    Directory of Open Access Journals (Sweden)

    Magdi El Fergani

    2017-12-01

    Full Text Available The one-pot production of succinic acid from glucose was investigated in pure hot water as solvent using Nb (0.02 and 0.05 moles%-Beta zeolites obtained by a post-synthesis methodology. Structurally, they are comprised of residual framework Al-acid sites, extra-framework isolated Nb (V and Nb2O5 pore-encapsulated clusters. The Nb-modified Beta-zeolites acted as bi-functional catalysts in which glucose is dehydrated to levulinic acid (LA which, further, suffers an oxidation process to succinic acid (SA. After the optimization of the reaction conditions, that is, at 180 °C, 18 bar O2, and 12 h reaction time, the oxidation of glucose occurred with a selectivity to succinic acid as high as 84% for a total conversion.

  1. A bifunctional ion-electron conducting interlayer for high energy density all-solid-state lithium-sulfur battery

    Science.gov (United States)

    Zhu, Yuewu; Li, Jie; Liu, Jin

    2017-05-01

    A bifunctional ion-electron conducting layer is designed for all-solid-state lithium-sulfur battery. This layer consists of electronic conductor and solid polymer electrolyte that is intercalated between the cathode and electrolyte. By forming a gradient of electrons and lithium ions, the electrochemical performance and interfacial compatibility of the battery are obviously enhanced. When a pure sulfur powder is directly used as an active material of the cathode, the battery with the interlayer delivers the initial discharge capacity of 1457 mAh g-1 and the discharge capacity of 792.8 mAh g-1 after 50 cycles at 0.5 C and 80 °C, while the battery with the same cathode and without the interlayer only has the discharge capacity of 291.9 mAh g-1 after the same number of cycles.

  2. Synthesis of a bifunctional cytidine derivative and its conjugation to RNA for in vitro selection of a cytidine deaminase ribozyme

    Directory of Open Access Journals (Sweden)

    Nico Rublack

    2014-08-01

    Full Text Available Over the past 20 years, the generation of functional RNAs by in vitro selection has become a standard technique. Apart from aptamers for simple binding of defined ligands, also RNAs for catalysis of chemical reactions have been selected. In the latter case, a key step often is the conjugation of one of the two reactants to the library, requiring suitable strategies for terminal or internal RNA functionalization. With the aim of selecting a ribozyme for deamination of cytidine, we have set up a selection scheme involving the attachment of the cytidine acting as deamination substrate to the 3'-terminus of the RNAs in the library, and library immobilization. Here, we report the synthesis of a bifunctional cytidine derivative suitable for conjugation to RNA and linkage of the conjugated library to a streptavidine-coated surface. Successful conjugation of the cytidine derivative to the 3'-terminus of a model RNA is demonstrated.

  3. The bifunctional aldehyde-alcohol dehydrogenase controls ethanol and acetate production in Entamoeba histolytica under aerobic conditions.

    Science.gov (United States)

    Pineda, Erika; Encalada, Rusely; Olivos-García, Alfonso; Néquiz, Mario; Moreno-Sánchez, Rafael; Saavedra, Emma

    2013-01-16

    By applying metabolic control analysis and inhibitor titration we determined the degree of control (flux control coefficient) of pyruvate:ferredoxin oxidoreductase (PFOR) and bifunctional aldehyde-alcohol dehydrogenase (ADHE) over the fluxes of fermentative glycolysis of Entamoeba histolytica subjected to aerobic conditions. The flux-control coefficients towards ethanol and acetate formation determined for PFOR titrated with diphenyleneiodonium were 0.07 and 0.09, whereas for ADHE titrated with disulfiram were 0.33 and -0.19, respectively. ADHE inhibition induced significant accumulation of glycolytic intermediates and lower ATP content. These results indicate that ADHE exerts significant flux-control on the carbon end-product formation of amoebas subjected to aerobic conditions. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  4. Antiferromagnetism, superconductivity and quantum oscillations in the bifunctional organic conductor κ-(BETS){sub 2}FeBr{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Scheidhammer, Ludwig; Kunz, Michael; Biberacher, Werner; Kartsovnik, Mark V. [Walther-Meissner-Institut, Garching (Germany); Kushch, Natasha D. [Institute of Problems of Chemical Physics, Chernogolovka (Russian Federation)

    2014-07-01

    The layered organic metal κ-(BETS){sub 2}FeBr{sub 4} is a bifunctional material that consists of organic layers containing a metallic π electron system and inorganic layers that carry localized magnetic moments. It shows an antiferromagnetic (AFM) transition with the Neel temperature T{sub N}∼2.5 K and a superconducting (SC) transition at the critical temperature T{sub c}∼1.1 K. Shubnikov-de Haas oscillations have been studied in both the normal metallic and AFM states at different magnetic field orientations. From the angle dependence of the oscillation amplitude the exchange field can be obtained. The comparison of the oscillations in AFM and normal metallic state yields information on the Fermi surface reconstruction in the AFM state. We also present the angle dependence of the metamagnetic transition and discuss its influence on superconductivity.

  5. Effects of support on bifunctional methanol oxidation pathways catalyzed by polyoxometallate keggin clusters

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Haichao; Iglesia, Enrique

    2003-12-26

    pathways catalyzed by acid sites. Secondary reactions leading to DMM and MF are strongly influenced by the chemical properties of support surfaces. Acidic SiO2 surfaces favored DMM formation, while amphoteric or dehydrogenating surfaces on ZrO2 and TiO2 led to MF formation, as a result of the varying role of each support in directing the reactions of HCHO and CH3OH and of the CH3OCH2OH intermediates toward DMM or MF, which was confirmed using physical catalyst pure support mixtures. These support effects reflect the bifunctional pathways of CH3OH reactions. These pathways are consistent with the effects of residence time and of the partial removal of H+ sites by titration using 2,6-di-tert-butyl pyridine.

  6. Bifunctional 3D Cu-MOFs containing glutarates and bipyridyl ligands: selective CO2 sorption and heterogeneous catalysis.

    Science.gov (United States)

    Hwang, In Hong; Bae, Jeong Mi; Kim, Wan-Seok; Jo, Young Dan; Kim, Cheal; Kim, Youngmee; Kim, Sung-Jin; Huh, Seong

    2012-11-07

    We report bifunctional three-dimensional (3D) Cu-MOFs with high selectivity of CO(2) over N(2) and H(2) as well as high catalytic activity for transesterification of esters. The Cu-MOFs containing Cu(2) dinuclear units connected by glutarates and bipyridyl ligands are formulated as [{Cu(2)(Glu)(2)(μ-bpa)}·(CH(3)CN)](n) (1) and [{Cu(2)(Glu)(2)(μ-bpp)}·(C(3)H(6)O)](n) (2) (Glu = glutarate, bpa = 1,2-bis(4-pyridyl)ethane, bpp = 1,3-bis(4-pyridyl)propane). These two new bifunctional 3D Cu-MOFs possess very similar pore shape with different pore dimensions. Their gas sorption behaviors were investigated by using CO(2), N(2) and H(2) at suitable temperatures. Both MOFs exhibited good CO(2) selectivity over N(2) and H(2). MOF 1 having a smaller pore dimension exhibited much higher CO(2) adsorption enthalpy than MOF 2 having a larger pore dimension. However, MOF 2 exhibited more enhanced CO(2) uptake ability than MOF 1. A subtle variation of pore dimension indeed influenced the CO(2) uptake ability somewhat significantly especially at higher temperatures such as 273 K and 298 K. Heterogeneous catalytic activities of the MOFs were also investigated in detail. Only MOF 1 appeared to be an efficient, mild, and easily recyclable heterogeneous catalyst for the transesterification of esters and constitutes a promising class of heterogeneous catalysts that allowed reuse without a significant loss of activity through twenty runs with ester.

  7. Bifunctional catalyst of graphite-encapsulated iron compound nanoparticle for magnetic carbon nanotubes growth by chemical vapor deposition

    Science.gov (United States)

    Saraswati, Teguh Endah; Prasiwi, Oktaviana Dewi Indah; Masykur, Abu; Anwar, Miftahul

    2017-01-01

    The carbon nanotube has widely taken great attractive in carbon nanomaterial research and application. One of its preparation methods is catalytic chemical vapor deposition (CCVD) using catalyst i.e. iron, nickel, etc. Generally, except the catalyst, carbon source gasses as the precursor are still required. Here, we report the use of the bifunctional material of Fe3O4/C which has an incorporated core/shell structures of carbon-encapsulated iron compound nanoparticles. The bifunctional catalyst was prepared by submerged arc discharge that simply performed using carbon and carbon/iron oxide electrodes in ethanol 50%. The prepared material was then used as a catalyst in thermal chemical vapor deposition at 800°C flown with ethanol vapor as the primer carbon source in a low-pressure condition. This catalyst might play a dual role as a catalyst and secondary carbon source for growing carbon nanotubes at the time. The synthesized products were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The successful formation of carbon nanotubes was assigned by the shifted X-ray diffracted peak of carbon C(002), the iron oxides of Fe3O4 and γ-Fe2O3, and the other peaks which were highly considered to the other carbon allotropes with sp2 hybridization structures. The other assignment was studied by electron microscopy which successfully observed the presence of single-wall carbon nanotubes. In addition, the as-prepared carbon nanotubes have a magnetic property which was induced by the remaining of metal catalyst inside the CNT.

  8. A Nanostructured Bifunctional platform for Sensing of Glucose Biomarker in Artificial Saliva: Synergy in hybrid Pt/Au surfaces.

    Science.gov (United States)

    Raymundo-Pereira, Paulo A; Shimizu, Flávio M; Coelho, Dyovani; Piazzeta, Maria H O; Gobbi, Angelo L; Machado, Sergio A S; Oliveira, Osvaldo N

    2016-12-15

    We report on a bimetallic, bifunctional electrode where a platinum (Pt) surface was patterned with nanostructured gold (Au) fingers with different film thicknesses, which was functionalized with glucose oxidase (GOx) to yield a highly sensitive glucose biosensor. This was achieved by using selective adsorption of a self-assembled monolayer (SAM) onto Au fingers, which allowed GOx immobilization only onto the Au-SAM surface. This modified electrode was termed bifunctional because it allowed to simultaneously immobilize the biomolecule (GOx) on gold to catalyze glucose, and detect hydrogen peroxide on Pt sites. Optimized electrocatalytic activity was reached for the architecture Pt/Au-SAM/GOx with 50nm thickness of Au, where synergy between Pt and Au allowed for detection of hydrogen peroxide (H2O2) at a low applied potential (0V vs. Ag/AgCl). Detection was performed for H2O2 in the range between 4.7 and 102.7 nmol L(-1), with detection limit of 3.4×10(-9) mol L(-1) (3.4 nmol L(-1)) and an apparent Michaelis-Menten rate constant of 3.2×10(-6)molL(-1), which is considerably smaller than similar devices with monometallic electrodes. The methodology was validated by measuring glucose in artificial saliva, including in the presence of interferents. The synergy between Pt and Au was confirmed in electrochemical impedance spectroscopy measurements with an increased electron transfer, compared to bare Pt and Au electrodes. The approach for fabricating the reproducible bimetallic Pt/Au electrodes is entirely generic and may be explored for other types of biosensors and biodevices where advantage can be taken of the combination of the two metals. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. VTC4 Is a Bifunctional Enzyme That Affects Myoinositol and Ascorbate Biosynthesis in Plants12[W][OA

    Science.gov (United States)

    Torabinejad, Javad; Donahue, Janet L.; Gunesekera, Bhadra N.; Allen-Daniels, Matthew J.; Gillaspy, Glenda E.

    2009-01-01

    Myoinositol synthesis and catabolism are crucial in many multiceullar eukaryotes for the production of phosphatidylinositol signaling molecules, glycerophosphoinositide membrane anchors, cell wall pectic noncellulosic polysaccharides, and several other molecules including ascorbate. Myoinositol monophosphatase (IMP) is a major enzyme required for the synthesis of myoinositol and the breakdown of myoinositol (1,4,5)trisphosphate, a potent second messenger involved in many biological activities. It has been shown that the VTC4 enzyme from kiwifruit (Actinidia deliciosa) has similarity to IMP and can hydrolyze l-galactose 1-phosphate (l-Gal 1-P), suggesting that this enzyme may be bifunctional and linked with two potential pathways of plant ascorbate synthesis. We describe here the kinetic comparison of the Arabidopsis (Arabidopsis thaliana) recombinant VTC4 with d-myoinositol 3-phosphate (d-Ins 3-P) and l-Gal 1-P. Purified VTC4 has only a small difference in the Vmax/Km for l-Gal 1-P as compared with d-Ins 3-P and can utilize other related substrates. Inhibition by either Ca2+ or Li+, known to disrupt cell signaling, was the same with both l-Gal 1-P and d-Ins 3-P. To determine whether the VTC4 gene impacts myoinositol synthesis in Arabidopsis, we isolated T-DNA knockout lines of VTC4 that exhibit small perturbations in abscisic acid, salt, and cold responses. Analysis of metabolite levels in vtc4 mutants showed that less myoinositol and ascorbate accumulate in these mutants. Therefore, VTC4 is a bifunctional enzyme that impacts both myoinositol and ascorbate synthesis pathways. PMID:19339506

  10. Striking hierarchical urchin-like peapoded NiCo2O4@C as advanced bifunctional electrocatalyst for overall water splitting

    Science.gov (United States)

    Deng, Ju; Zhang, Huijuan; Zhang, Yan; Luo, Pan; Liu, Li; Wang, Yu

    2017-12-01

    Developing bifunctional electrocatalysts with features of wide source, low price and high efficiency for overall water splitting has the extremely vital significance on the energy front. Herein, we have designed and fabricated urchin-like peapoded NiCo2O4@C architecture for the first time, playing a prominent role in bifunctional alkaline catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 M NaOH ascribed to outstanding catalytic performance and good stability. When the urchin-like peapoded NiCo2O4@C electrodes are integrated into the two-electrode system for alkaline overall water splitting, the potential as small as ∼1.608 V is a requisite for the current density of 10 mA cm-2. Given high activity and long-term stability, the harvested urchin-like peapoded NiCo2O4@C is of great potential for practical application.

  11. Synthesis of steroid-biaryl ether hybrid macrocycles with high skeletal and side chain variability by multiple multicomponent macrocyclization including bifunctional building blocks.

    Science.gov (United States)

    Wessjohann, Ludger A; Rivera, Daniel G; Coll, Francisco

    2006-09-29

    Utilizing the multiple multicomponent macrocyclization including bifunctional building blocks (MiB) strategy, a library of nonracemic, nonrepetitive peptoid-containing steroid-biaryl ether hybrid macrocycles was built. Up to 16 new bonds, including those of the macrocyclization, can be formed in one pot simultaneously while introducing varied elements of diversity. Functional diversity is generated primarily by choosing Ugi-reactive functional building blocks, bearing the respective recognition or catalytic motifs. These appear attached to the peptoid backbone of the macrocyclic cavity, similar to side chains of amino acids found in enzyme active sites. Likewise, skeletal diversity is based on the variation of defined bifunctional building blocks which allow the parallel formation of macrocyclic cavities that are highly diverse in shape and size and thus perspectively in function. This straightforward approach is suitable to generate multifunctional macrocycles for applications in catalysis, supramolecular, or biological chemistry.

  12. All-optical OR/NOR Bi-functional logic gate by using cross-gain modulation in semiconductor optical amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Sun; Byun, Young Tae; Lee, Seok; Jhon, Young Min [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2010-04-15

    An OR/NOR bi-functional all-optical logic gate has been experimentally demonstrated at 10 Gbit/s by using cross-gain modulation (XGM) in only 2 semiconductor optical amplifiers (SOAs). One SOA was used for NOR operation and the other SOA was used for inversion to obtain OR operation. Numerical simulation has also been performed, which coincided well with the experimental results.

  13. Catalytic Asymmetric Synthesis of Both Enantiomers of 4‑Substituted 1,4-Dihydropyridines with the Use of Bifunctional Thiourea-Ammonium Salts Bearing Different Counterions

    Directory of Open Access Journals (Sweden)

    Kohzo Yoshida

    2010-11-01

    Full Text Available Organoammonium salts composed of a Brønsted acid and an anilinothiourea promoted the Michael addition of β-keto esters and α,β-unsaturated aldehydes in the presence of primary amines to give functionalized 1,4-dihydropyridines enantioselectively. With the use of the different Brønsted acids such as DFA and HBF4 with the same bifunctional thiourea, both enantiomers of 4-substituted 1,4-dihydropyridine were synthesized from the same starting materials.

  14. Enzyme-mediated coupling of a bi-functional phenolic compound onto wool to enhance its physical, mechanical and functional properties

    OpenAIRE

    Gaffar Hossain, Kh. M.; Díaz González, María; Riva Juan, Ascensión; Tzanov, Tzanko

    2009-01-01

    Electronic version of an article published as "Enzyme and microbial technology", 08 Desembre 2009, p. 1-5 Wool fibres have been modified with nordihydroguaiaretic acid (NDGA) to improve their performance at use. This water insoluble bi-functional phenolic compound has been grafted on wool through a laccase enzyme catalyzed reaction in an aqueous-ethanol mixture. The capacity of laccase to oxidise NDGA in this aqueous-organic medium has been studied electrochemicaly. The increase of CH2, CH...

  15. Self-association free bifunctional thiourea organocatalysts: synthesis of chiral α-amino acids via dynamic kinetic resolution of racemic azlactones.

    Science.gov (United States)

    Oh, Joong-Suk; Lee, Ji-Woong; Ryu, Tae Hee; Lee, Jae Heon; Song, Choong Eui

    2012-02-07

    Concentration-independent high enantioselectivity in the dynamic kinetic resolution (DKR) of racemic azlactones affording chiral α-aminoesters has been achieved using self-association free thiourea-based dimeric cinchona alkaloid organocatalysts. Detailed experimental studies and single crystal X-ray analysis confirmed that these bifunctional organocatalysts I do not form H-bonded self-aggregates in either solution or solid state.

  16. Enantioselective synthesis of 2,3-disubstituted trans-2,3-dihydrobenzofurans using a Brønsted base/thiourea bifunctional catalyst.

    Science.gov (United States)

    Barrios Antúnez, Diego-Javier; Greenhalgh, Mark D; Fallan, Charlene; Slawin, Alexandra M Z; Smith, Andrew D

    2016-07-26

    The diastereo- and enantioselective synthesis of 2,3-disubstituted trans-2,3-dihydrobenzofuran derivatives (15 examples, up to 96 : 4 dr, 95 : 5 er) via intramolecular Michael addition has been developed using keto-enone substrates and a bifunctional tertiary amine-thiourea catalyst. This methodology was extended to include non-activated ketone pro-nucleophiles for the synthesis of 2,3-disubstituted indane and 3,4-disubstituted tetrahydrofuran derivatives.

  17. Hierarchically Designed 3D Holey C2N Aerogels as Bifunctional Oxygen Electrodes for Flexible and Rechargeable Zn-Air Batteries.

    Science.gov (United States)

    Shinde, Sambhaji S; Lee, Chi Ho; Yu, Jin-Young; Kim, Dong-Hyung; Lee, Sang Uck; Lee, Jung-Ho

    2018-01-23

    The future of electrochemical energy storage spotlights on the designed formation of highly efficient and robust bifunctional oxygen electrocatalysts that facilitate advanced rechargeable metal-air batteries. We introduce a scalable facile strategy for the construction of a hierarchical three-dimensional sulfur-modulated holey C2N aerogels (S-C2NA) as bifunctional catalysts for Zn-air and Li-O2 batteries. The S-C2NA exhibited ultrahigh surface area (∼1943 m2 g-1) and superb electrocatalytic activities with lowest reversible oxygen electrode index ∼0.65 V, outperforms the highly active bifunctional and commercial (Pt/C and RuO2) catalysts. Density functional theory and experimental results reveal that the favorable electronic structure and atomic coordination of holey C-N skeleton enable the reversible oxygen reactions. The resulting Zn-air batteries with liquid electrolytes and the solid-state batteries with S-C2NA air cathodes exhibit superb energy densities (958 and 862 Wh kg-1), low charge-discharge polarizations, excellent reversibility, and ultralong cycling lives (750 and 460 h) than the commercial Pt/C+RuO2 catalysts, respectively. Notably, Li-O2 batteries with S-C2NA demonstrated an outstanding specific capacity of ∼648.7 mA h g-1 and reversible charge-discharge potentials over 200 cycles, illustrating great potential for commercial next-generation rechargeable power sources of flexible electronics.

  18. Engineering of restriction endonucleases: using methylation activity of the bifunctional endonuclease Eco57I to select the mutant with a novel sequence specificity.

    Science.gov (United States)

    Rimseliene, Renata; Maneliene, Zita; Lubys, Arvydas; Janulaitis, Arvydas

    2003-03-21

    Type II restriction endonucleases (REs) are widely used tools in molecular biology, biotechnology and diagnostics. Efforts to generate new specificities by structure-guided design and random mutagenesis have been unsuccessful so far. We have developed a new procedure called the methylation activity-based selection (MABS) for generating REs with a new specificity. MABS uses a unique property of bifunctional type II REs to methylate DNA targets they recognize. The procedure includes three steps: (1) conversion of a bifunctional RE into a monofunctional DNA-modifying enzyme by cleavage center disruption; (2) mutagenesis and selection of mutants with altered DNA modification specificity based on their ability to protect predetermined DNA targets; (3) reconstitution of the cleavage center's wild-type structure. The efficiency of the MABS technique was demonstrated by altering the sequence specificity of the bifunctional RE Eco57I from 5'-CTGAAG to 5'-CTGRAG, and thus generating the mutant restriction endonuclease (and DNA methyltransferase) of a specificity not known before. This study provides evidence that MABS is a promising technique for generation of REs with new specificities.

  19. Self-assembly of cobalt-centered metal organic framework and multiwalled carbon nanotubes hybrids as a highly active and corrosion-resistant bifunctional oxygen catalyst

    Science.gov (United States)

    Fang, Yiyun; Li, Xinzhe; Li, Feng; Lin, Xiaoqing; Tian, Min; Long, Xuefeng; An, Xingcai; Fu, Yan; Jin, Jun; Ma, Jiantai

    2016-09-01

    Metal organic frameworks (MOF) derived carbonaceous materials have emerged as promising bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts for electrochemical energy conversion and storage. But previous attempts to overcome the poor electrical conductivity of MOFs hybrids involve a harsh high-template pyrolytic process to in situ form carbon, which suffer from extremely complex operation and inevitable carbon corrosion at high positive potentials when OER is operated. Herein, a self-assembly approach is presented to synthesize a non-precious metal-based, high active and strong durable Co-MOF@CNTs bifunctional catalyst for OER and ORR. CNTs not only improve the transportation of the electrons but also can sustain the harsh oxidative environment of OER without carbon corrosion. Meanwhile, the unique 3D hierarchical structure offers a large surface area and stable anchoring sites for active centers and CNTs, which enables the superior durability of hybrid. Moreover, a synergistic catalysis of Co(II), organic ligands and CNTs will enhance the bifunctional electrocatalytic performance. Impressively, the hybrid exhibits comparable OER and ORR catalytic activity to RuO2 and 20 wt% Pt/C catalysts and superior stability. This facile and versatile strategy to fabricating MOF-based hybrids may be extended to other electrode materials for fuel cell and water splitting applications.

  20. Achieving rapid Li-ion insertion kinetics in TiO2 mesoporous nanotube arrays for bifunctional high-rate energy storage smart windows.

    Science.gov (United States)

    Tong, Zhongqiu; Liu, Shikun; Li, Xingang; Mai, Liqiang; Zhao, Jiupeng; Li, Yao

    2018-01-31

    Smart electrochromic windows integrated with electrochemical energy storage capacity are receiving increasing interest for green buildings. However, the fabrication of bifunctional devices that demonstrate high-rate capability with stable and desirable optical modulation still remains a great challenge. Herein, a facile sacrificial template-accelerated hydrolysis approach is presented to prepare a designed lithium-ion insertion-type material layer on a fluorine-doped tin oxide substrate, with TiO2 mesoporous nanotube array (MNTA) film as an example, with rapid Li-ion insertion kinetics and without sacrificing window transparency, to meet requirements. A bifunctional device is assembled to exhibit the optical-electrochemical superiority of MNTA nanostructures. The as-assembled bifunctional smart window exhibits strong electrochromic contrast and high-rate capability in the fast galvanostatic charge/discharge process. For instance, at 1 A g-1, it completes the charge or discharge process within only 232 s and delivers a high, reversible and stable specific capacity of 60 mA h g-1, accompanying obvious transmittance modulation in the visible spectrum, with a typical value of ca. 30.4% at 700 nm, and strong color changes between deep blue and transparency.

  1. From Chlorella to Nestlike Framework Constructed with Doped Carbon Nanotubes: A Biomass-Derived, High-Performance, Bifunctional Oxygen Reduction/Evolution Catalyst.

    Science.gov (United States)

    Wang, Guanghua; Deng, Yijie; Yu, Jinnan; Zheng, Long; Du, Li; Song, Huiyu; Liao, Shijun

    2017-09-20

    The development of effective bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is significant for energy conversion systems, such as Li-air batteries, fuel cells, and water splitting technologies. Herein, a Chlorella-derived catalyst with a nestlike framework, composed of bamboolike nanotubes that encapsulate cobalt nanoparticles, has been prepared through a facile pyrolysis process. It achieves perfect bifunctional catalysis both in ORR and OER on a single catalyst. For our optimal catalyst Co/M-Chlorella-900, its ORR half-wave potential is positively shifted by 40 mV compared to that of a commercial Pt/C catalyst, and the overpotential at 10 mA cm -2 for the OER is 23 mV lower than that of a commercial IrO 2 /C catalyst in an alkaline medium. This superior bifunctional catalytic performance is benefited from the simultaneous increase of pyridinic N sites for ORR and graphitic N sites for OER. In addition, N-doped carbon-encapsulated Co nanoparticles improve both ORR and OER performance by forming new active centers. The unique nestlike carbon nanotube framework not only afforded highly dense ORR and OER active sites but also promoted the electron and mass transfer. Our catalyst also displays notable durability during the ORR and OER, making it promising for use in ORR/OER-related energy conversion systems.

  2. An Efficient Bifunctional Electrocatalyst for a Zinc-Air Battery Derived from Fe/N/C and Bimetallic Metal-Organic Framework Composites.

    Science.gov (United States)

    Wang, Mengfan; Qian, Tao; Zhou, Jinqiu; Yan, Chenglin

    2017-02-15

    Efficient bifunctional electrocatalysts with desirable oxygen activities are closely related to practical applications of renewable energy systems including metal-air batteries, fuel cells, and water splitting. Here a composite material derived from a combination of bimetallic zeolitic imidazolate frameworks (denoted as BMZIFs) and Fe/N/C framework was reported as an efficient bifunctional catalyst. Although BMZIF or Fe/N/C alone exhibits undesirable oxygen reaction activity, a combination of these materials shows unprecedented ORR (half-wave potential of 0.85 V as well as comparatively superior OER activities (potential@10 mA cm -2 of 1.64 V), outperforming not only a commercial Pt/C electrocatalyst but also most reported bifunctional electrocatalysts. We then tested its practical application in Zn-air batteries. The primary batteries exhibit a high peak power density of 235 mW cm -2 , and the batteries are able to be operated smoothly for 100 cycles at a curent density of 10 mA cm -2 . The unprecedented catalytic activity can be attritued to chemical coupling effects between Fe/N/C and BMZIF and will aid the development of highly active electrocatalysts and applications for electrochemical energy devices.

  3. Ni3 FeN-Supported Fe3 Pt Intermetallic Nanoalloy as a High-Performance Bifunctional Catalyst for Metal-Air Batteries.

    Science.gov (United States)

    Cui, Zhiming; Fu, Gengtao; Li, Yutao; Goodenough, John B

    2017-08-07

    Electrocatalysts for both the oxygen reduction and evolution reactions (ORR and OER) are vital for the performances of rechargeable metal-air batteries. Herein, we report an advanced bifunctional oxygen electrocatalyst consisting of porous metallic nickel-iron nitride (Ni3 FeN) supporting ordered Fe3 Pt intermetallic nanoalloy. In this hybrid catalyst, the bimetallic nitride Ni3 FeN mainly contributes to the high activity for the OER while the ordered Fe3 Pt nanoalloy contributes to the excellent activity for the ORR. Robust Ni3 FeN-supported Fe3 Pt catalysts show superior catalytic performance to the state-of-the-art ORR catalyst (Pt/C) and OER catalyst (Ir/C). The Fe3 Pt/Ni3 FeN bifunctional catalyst enables Zn-air batteries to achieve a long-term cycling performance of over 480 h at 10 mA cm-2 with high efficiency. The extraordinarily high performance of the Fe3 Pt/Ni3 FeN bifunctional catalyst makes it a very promising air cathode in alkaline electrolyte. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Fe2.25W0.75O4/reduced graphene oxide nanocomposites for novel bifunctional photocatalyst: One-pot synthesis, magnetically recyclable and enhanced photocatalytic property

    Science.gov (United States)

    Guo, Jinxue; Jiang, Bin; Zhang, Xiao; Zhou, Xiaoyu; Hou, Wanguo

    2013-09-01

    Fe2.25W0.75O4/reduced graphene oxide (RGO) composites were prepared for application of novel bifunctional photocatalyst via simple one-pot hydrothermal method, employing graphene oxide (GO), Na2WO4, FeSO4 and sodium dodecyl benzene sulfonate (SDBS) as the precursors. Transmission electron microscope (TEM) results indicate that the well-dispersed Fe2.25W0.75O4 nanoparticles were deposited on the surface of RGO sheets homogeneously. Magnetic characterization reveals that Fe2.25W0.75O4 and Fe2.25W0.75O4/RGO show ferromagnetic behaviors. So this novel bifunctional photocatalyst could achieve magnetic separation and collection with the aid of external magnet. The composites exhibit enhanced photocatalytic performance on degradation of methyl orange (MO) compared with pure Fe2.25W0.75O4 under low-power ultraviolet light irradiation due to the introduction of RGO. Moreover, this hybrid catalyst possesses long-term excellent photocatalytic performance due to its good thermal stability. This bifunctional photocatalyst, which combines magnetic property and excellent photocatalytic activity, would be a perfect candidate in applications of catalytic elimination of environmental pollutants and other areas.

  5. Bifunctional TaqII restriction endonuclease: redefining the prototype DNA recognition site and establishing the Fidelity Index for partial cleaving

    Directory of Open Access Journals (Sweden)

    Żylicz-Stachula Agnieszka

    2011-12-01

    Full Text Available Abstract Background The TaqII enzyme is a member of the Thermus sp. enzyme family that we propounded previously within Type IIS restriction endonucleases, containing related thermophilic bifunctional endonucleases-methyltransferases from various Thermus sp.: TaqII, Tth111II, TthHB27I, TspGWI, TspDTI and TsoI. These enzymes show significant nucleotide and amino acid sequence similarities, a rare phenomenon among restriction endonucleases, along with similarities in biochemical properties, molecular size, DNA recognition sequences and cleavage sites. They also feature some characteristics of Types I and III. Results Barker et al. reported the Type IIS/IIC restriction endonuclease TaqII as recognizing two distinct cognate site variants (5'-GACCGA-3' and 5'-CACCCA-3' while cleaving 11/9 nucleotides downstream. We used four independent methods, namely, shotgun cloning and sequencing, restriction pattern analysis, digestion of particular custom substrates and GeneScan analysis, to demonstrate that the recombinant enzyme recognizes only 5'-GACCGA-3' sites and cleaves 11/9 nucleotides downstream. We did not observe any 5'-CACCCA-3' cleavage under a variety of conditions and site arrangements tested. We also characterized the enzyme biochemically and established new digestion conditions optimal for practical enzyme applications. Finally, we developed and propose a new version of the Fidelity Index - the Fidelity Index for Partial Cleavage (FI-PC. Conclusions The DNA recognition sequence of the bifunctional prototype TaqII endonuclease-methyltransferase from Thermus aquaticus has been redefined as recognizing only 5'-GACCGA-3' cognate sites. The reaction conditions (pH and salt concentrations were designed either to minimize (pH = 8.0 and 10 mM ammonium sulphate or to enhance star activity (pH = 6.0 and no salt. Redefinition of the recognition site and reaction conditions makes this prototype endonuclease a useful tool for DNA manipulation; as yet, this

  6. Bifunctional TaqII restriction endonuclease: redefining the prototype DNA recognition site and establishing the Fidelity Index for partial cleaving.

    Science.gov (United States)

    Zylicz-Stachula, Agnieszka; Zołnierkiewicz, Olga; Sliwińska, Katarzyna; Jeżewska-Frąckowiak, Joanna; Skowron, Piotr M

    2011-12-05

    The TaqII enzyme is a member of the Thermus sp. enzyme family that we propounded previously within Type IIS restriction endonucleases, containing related thermophilic bifunctional endonucleases-methyltransferases from various Thermus sp.: TaqII, Tth111II, TthHB27I, TspGWI, TspDTI and TsoI. These enzymes show significant nucleotide and amino acid sequence similarities, a rare phenomenon among restriction endonucleases, along with similarities in biochemical properties, molecular size, DNA recognition sequences and cleavage sites. They also feature some characteristics of Types I and III. Barker et al. reported the Type IIS/IIC restriction endonuclease TaqII as recognizing two distinct cognate site variants (5'-GACCGA-3' and 5'-CACCCA-3') while cleaving 11/9 nucleotides downstream. We used four independent methods, namely, shotgun cloning and sequencing, restriction pattern analysis, digestion of particular custom substrates and GeneScan analysis, to demonstrate that the recombinant enzyme recognizes only 5'-GACCGA-3' sites and cleaves 11/9 nucleotides downstream. We did not observe any 5'-CACCCA-3' cleavage under a variety of conditions and site arrangements tested. We also characterized the enzyme biochemically and established new digestion conditions optimal for practical enzyme applications. Finally, we developed and propose a new version of the Fidelity Index - the Fidelity Index for Partial Cleavage (FI-PC). The DNA recognition sequence of the bifunctional prototype TaqII endonuclease-methyltransferase from Thermus aquaticus has been redefined as recognizing only 5'-GACCGA-3' cognate sites. The reaction conditions (pH and salt concentrations) were designed either to minimize (pH = 8.0 and 10 mM ammonium sulphate) or to enhance star activity (pH = 6.0 and no salt). Redefinition of the recognition site and reaction conditions makes this prototype endonuclease a useful tool for DNA manipulation; as yet, this enzyme has no practical applications. The extension of

  7. Cofactor Specificity of the Bifunctional Alcohol and Aldehyde Dehydrogenase (AdhE) in Wild-Type and Mutant Clostridium thermocellum and Thermoanaerobacterium saccharolyticum

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Tianyong; Olson, Daniel G.; Tian, Liang; Bomble, Yannick J.; Himmel, Michael E.; Lo, Jonathan; Hon, Shuen; Shaw, A. Joe; van Dijken, Johannes P.; Lynd, Lee R.; Metcalf, W. W.

    2015-05-26

    . When single amino acid mutations in AdhE that caused increased NADPH-linked ADH activity were introduced intoC. thermocellumandT. saccharolyticum, ethanol production increased in both organisms. Structural analysis of the wild-type and mutant AdhE proteins was performed to provide explanations for the cofactor specificity change on a molecular level. This work describes the characterization of the AdhE enzyme from different strains ofC. thermocellumandT. saccharolyticum.C. thermocellumandT. saccharolyticumare thermophilic anaerobes that have been engineered to make high yields of ethanol and can solubilize components of plant biomass and ferment the sugars to ethanol. In the course of engineering these strains, several mutations arose in the bifunctional ADH/ALDH protein AdhE, changing both enzyme activity and cofactor specificity. We show that changing AdhE cofactor specificity from mostly NADH linked to mostly NADPH linked resulted in higher ethanol production byC. thermocellumandT. saccharolyticum.

  8. An evolutionary perspective on protein moonlighting.

    Science.gov (United States)

    Copley, Shelley D

    2014-12-01

    Moonlighting proteins serve one or more novel functions in addition to their canonical roles. Moonlighting functions arise when an adventitious interaction between a protein and a new partner improves fitness of the organism. Selective pressure for improvement in the new function can result in two alternative outcomes. The gene encoding the newly bifunctional protein may duplicate and diverge so as to encode two proteins, each of which serves only one function. Alternatively, genetic changes that minimize adaptive conflict between the two functions and/or improve control over the time and place at which each function is served can lead to a moonlighting protein. Importantly, genetic changes that enhance a moonlighting function can occur in the gene encoding the moonlighting protein itself, in a gene that affects the structure of its new partner or in a gene encoding a transcription factor that controls expression of either partner. The evolutionary history of each moonlighting protein is complex, depending on the stochastic occurrence of genetic changes such as gene duplication and point mutations, and the effects of those changes on fitness. Population effects, particularly loss of promising individuals due to random genetic drift, also play a role in the emergence of a moonlighting protein. The ultimate outcome is not necessarily the 'optimal' solution to the problem of serving two functions, but may be 'good enough' so that fitness becomes limited by some other function.

  9. Pluronic-lysozyme conjugates as anti-adhesive and antibacterial bifunctional polymers for surface coating

    NARCIS (Netherlands)

    Muszanska, Agnieszka K.; Busscher, Henk J.; Herrmann, Andreas; van der Mei, Henny C.; Norde, Willem

    This paper describes the preparation and characterization of polymer protein conjugates composed of a synthetic triblock copolymer with a central polypropylene oxide (PPO) block and two terminal polyethylene oxide (PEO) segments, Pluronic F-127, and the antibacterial enzyme lysozyme attached to the

  10. Crumpled rGO-supported Pt-Ir bifunctional catalyst prepared by spray pyrolysis for unitized regenerative fuel cells

    Science.gov (United States)

    Kim, In Gyeom; Nah, In Wook; Oh, In-Hwan; Park, Sehkyu

    2017-10-01

    Three-dimensional (3D) crumpled reduced graphene oxide supported Pt-Ir alloys that served as bifunctional oxygen catalysts for use in untized regenerative fuel cells were synthesized by a facile spray pyrolysis method. Pt-Ir catalysts supported on rGO (Pt-Ir/rGOs) were physically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) to observe change in composition by heat treatment, alloying, and morphological transition of the catalysts. Their catalytic activities and stabilities for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) conditions were electrochemically investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), potential cycling and hold tests on the rotating disk electrode (RDE). Pt-Ir/rGO with no post heat-treatment (Pt-Ir/rGO_NP) showed a lower activity for ORR and OER although metal nanoparticles decorated on the support are relatively small. However, Pt-Ir/rGO showed remarkably enhanced activity following heat treatment, depending on temperature. Pt-Ir/rGO heat-treated at 600 °C after spray pyrolysis (Pt-Ir/rGO_P600) exhibited a higher activity and stability than a commercially available Pt/C catalyst kept under the ORR condition, and it also revealed a comparable OER activity and durability versus the commercial unsupported Ir catalyst.

  11. Crystal structure of the 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase•dihydropteroate synthase bifunctional enzyme from Francisella tularensis.

    Directory of Open Access Journals (Sweden)

    Charles W Pemble

    2010-11-01

    Full Text Available The 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK and dihydropteroate synthase (DHPS enzymes catalyze sequential metabolic reactions in the folate biosynthetic pathway of bacteria and lower eukaryotes. Both enzymes represent validated targets for the development of novel anti-microbial therapies. We report herein that the genes which encode FtHPPK and FtDHPS from the biowarfare agent Francisella tularensis are fused into a single polypeptide. The potential of simultaneously targeting both modules with pterin binding inhibitors prompted us to characterize the molecular details of the multifunctional complex. Our high resolution crystallographic analyses reveal the structural organization between FtHPPK and FtDHPS which are tethered together by a short linker. Additional structural analyses of substrate complexes reveal that the active sites of each module are virtually indistinguishable from those of the monofunctional enzymes. The fused bifunctional enzyme therefore represents an excellent vehicle for finding inhibitors that engage the pterin binding pockets of both modules that have entirely different architectures. To demonstrate that this approach has the potential of producing novel two-hit inhibitors of the folate pathway, we identify and structurally characterize a fragment-like molecule that simultaneously engages both active sites. Our study provides a molecular framework to study the enzyme mechanisms of HPPK and DHPS, and to design novel and much needed therapeutic compounds to treat infectious diseases.

  12. Three-dimensional radial α-MnO2 synthesized from different redox potential for bifunctional oxygen electrocatalytic activities

    Science.gov (United States)

    Zheng, Xiaoying; Yu, Lin; Lan, Bang; Cheng, Gao; Lin, Ting; He, Binbin; Ye, Wenjin; Sun, Ming; Ye, Fei

    2017-09-01

    The morphology of manganese dioxides has great effects on their electrocatalytic activities. Herein, two different types of three-dimensional (3D) radial α-MnO2 (dandelion- and urchin-like) catalysts are readily fabricated via two different redox reactions through the hydrothermal method, and their electrocatalytic activities are studied for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). As a result, the dandelion-like α-MnO2 exhibits a higher electrocatalytic performance than urchin-like α-MnO2, with a lower overpotential (20 mV lower for ORR and 90 mV lower for OER), higher mass activity and lower Tafel slope. The excellent electrocatalytic activity of dandelion-like α-MnO2 can be attributed to its relatively larger BET and electrochemical active surface area, richer defects, higher amount of Mn3+, and less charge transfer resistance. Our results shed insights into developing new way in constructing the deficient α-MnO2 bifunctional oxygen electrocatalysts.

  13. Voltammetric determination of Cd{sup 2+} based on the bifunctionality of single-walled carbon nanotubes-Nafion film

    Energy Technology Data Exchange (ETDEWEB)

    Sun Dong [Department of Pharmacy, Wenzhou Medical College, Wenzhou 325000 (China) and Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)]. E-mail: sun_dong11@163.com; Xie Xiafeng [Department of Pharmacy, Wenzhou Medical College, Wenzhou 325000 (China); Cai Yuepiao [Department of Pharmacy, Wenzhou Medical College, Wenzhou 325000 (China); Zhang Huajie [Department of Pharmacy, Wenzhou Medical College, Wenzhou 325000 (China); Wu Kangbing [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2007-01-02

    In the presence of Nafion, single-walled carbon nanotubes (SWNTs) were easily dispersed into ethanol, resulting in a homogeneous SWNTs/Nafion suspension. After evaporating ethanol, a SWNTs/Nafion film with bifunctionality was constructed onto glassy carbon electrode (GCE) surface. Attributing to the strong cation-exchange ability of Nafion and excellent properties of SWNTs, the SWNTs/Nafion film-coated GCE remarkably enhances the sensitivity of determination of Cd{sup 2+}. Based on this, an electrochemical method was developed for the determination of trace levels of Cd{sup 2+} by anodic stripping voltammetry (ASV). In pH 5.0 NaAc-HAc buffer, Cd{sup 2+} was firstly exchanged and adsorbed onto SWNTs/Nafion film surface, and then reduce at -1.10 V. During the positive potential sweep, reduced cadmium was oxidized, and a well-defined stripping peak appeared at -0.84 V, which can be used as analytical signal for Cd{sup 2+}. The linear range is found to be from 4.0 x 10{sup -8} to 4.0 x 10{sup -6} mol L{sup -1}, and the lowest detectable concentration is estimated to be 4.0 x 10{sup -9} mol L{sup -1}. Finally, this method was successfully employed to detect Cd{sup 2+} in water samples.

  14. Monolith dip-it: a bifunctional device for improving the sensitivity of direct analysis in real time mass spectrometry.

    Science.gov (United States)

    Li, Xianjiang; Li, Ze; Wang, Xin; Nie, Honggang; Zhang, Yiding; Bai, Yu; Liu, Huwei

    2016-08-02

    A bifunctional monolith dip-it was fabricated and applied for improving the sensitivity of direct analysis in real time mass spectrometry (DART-MS). This monolith dip-it device was prepared by in situ polymerization of poly(BMA-EDMA-MAA) monolith in the glass capillary of dip-it. As a solid-phase microextraction (SPME) device, it showed strong affinity to four Sudan dyes through hydrophilic interaction and hydrogen bond interaction. As a sample loading device, it could be directly analyzed by DART-MS without organic solvent elution or laser desorption. As a result, this device is environmentally friendly, and used for fast analysis. Under optimized conditions, the limits of detection for four analytes were 5-10 ng mL(-1) and the linear ranges covered more than two orders of magnitude. Finally, the developed method has been applied for the analysis of chili powder and the recoveries for spiked analytes were in the range of 83.2% to 115.1% demonstrating that this device is an efficient sampler for DART-MS analysis and the proposed method could find more applications in different areas like food analysis.

  15. Phenyl and ionic liquid based bifunctional periodic mesoporous organosilica supported copper: An efficient nanocatalyst for clean production of polyhydroquinolines.

    Science.gov (United States)

    Elhamifar, Dawood; Ardeshirfard, Hakimeh

    2017-11-01

    A novel phenyl and ionic liquid based bifunctional periodic mesoporous organosilica supported copper (Cu@BPMO-Ph-IL) is prepared, characterized and its catalytic application is developed in the clean production of polyhydroquinolines. The Cu@BPMO-Ph-IL was prepared via chemical grafting of ionic liquid groups onto phenyl-based PMO followed by treatment with copper acetate. This nanocatalyst was characterized with transmission electron microscopy (TEM), scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs), thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD), nitrogen-sorption and energy dispersive X-ray (EDX) analyses. This was successfully applied in the one-pot Hantzsch condensation of aldehydes, ammonium acetate, alkylacetoacetates and dimedone to prepare a set of different derivatives of polyhydroquinolines in high yields and selectivity. The catalyst was effectively recovered and reused several times without important decrease in efficiency. The recovered catalyst was also characterized with TEM analysis to study its stability and durability under applied conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Two-Step Hydrothermal Synthesis of Bifunctional Hematite-Silver Heterodimer Nanoparticles for Potential Antibacterial and Anticancer Applications

    Science.gov (United States)

    Trang, Vu Thi; Tam, Le Thi; Phan, Vu Ngoc; Van Quy, Nguyen; Huy, Tran Quang; Le, Anh-Tuan

    2017-06-01

    In recent years, the development of composite nanostructures containing noble metal and magnetic nanocrystals has attracted much interest because they offer a promising avenue for multifunctional applications in nanomedicine and pharmacotherapy. In this work, we present a facile two-step hydrothermal approach for the synthesis of bifunctional heterodimer nanoparticles (HDNPs) composed of hematite nanocubes (α-Fe2O3 NCs) and silver nanoparticles (Ag-NPs). The formation and magnetic property of α-Fe2O3-Ag HDNPs was analyzed by transmission electron microscopy, x-ray diffraction and vibrating sample magnetometer. Interestingly, the hydrothermal-synthesized α-Fe2O3-Ag HDNPs were found to display significant antibacterial activity against three types of infectious bacteria. The cytotoxicity of α-Fe2O3-Ag nanocomposite against lung cancer A549 cell line was investigated and compared with that of pure α-Fe2O3 NCs and Ag-NPs. The obtained results reveal that the α-Fe2O3-Ag nanocomposite exhibited higher anticancer performance than that of pure Ag-NPs, whereas pure α-Fe2O3 NCs were not cytotoxic to the tested cells. The inhibitory concentration (IC50) of the α-Fe2O3-Ag nanocomposite was found at 20.94 μg/mL. With the aforementioned properties, α-Fe2O3-Ag HDNPs showed a high potential as a multifunctional material for advanced biomedicine and nanotherapy applications.

  17. Bifunctional Molecular Photoswitches Based on Overcrowded Alkenes for Dynamic Control of Catalytic Activity in Michael Addition Reactions.

    Science.gov (United States)

    Pizzolato, Stefano F; Collins, Beatrice S L; van Leeuwen, Thomas; Feringa, Ben L

    2017-05-02

    The emerging field of artificial photoswitchable catalysis has recently shown striking examples of functional light-responsive systems allowing for dynamic control of activity and selectivity in organocatalysis and metal-catalysed transformations. While our group has already disclosed systems featuring first generation molecular motors as the switchable central core, a design based on second generation molecular motors is lacking. Here, the syntheses of two bifunctionalised molecular switches based on a photoresponsive tetrasubstituted alkene core are reported. They feature a thiourea substituent as hydrogen-donor moiety in the upper half and a basic dimethylamine group in the lower half. This combination of functional groups offers the possibility for application of these molecules in photoswitchable catalytic processes. The light-responsive central cores were synthesized by a Barton-Kellogg coupling of the prefunctionalized upper and lower halves. Derivatization using Buchwald-Hartwig amination and subsequent introduction of the thiourea substituent afforded the target compounds. Control of catalytic activity in the Michael addition reaction between (E)-3-bromo-β-nitrostyrene and 2,4-pentanedione is achieved upon irradiation of stable-(E) and stable-(Z) isomers of the bifunctional catalyst 1. Both isomers display a decrease in catalytic activity upon irradiation to the metastable state, providing systems with the potential to be applied as ON/OFF catalytic photoswitches. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The synthesis and properties of bifunctional and intelligent Fe3O4@titanium oxide core/shell nanoparticles.

    Science.gov (United States)

    Yin, Yichao; Liu, Chenjie; Wang, Baoxiang; Yu, Shoushan; Chen, Kezheng

    2013-05-21

    A simple, one-pot solvothermal method has been demonstrated for the preparation of bifunctional Fe3O4@titanium oxide core/shell nanoparticles. In a typical procedure, tetraalkoxyl titanium Ti(OC4H9)4 and FeCl3 as precursors were added into ethylene glycol and further solvothermal treatment was used to synthesize the core/shell particles. The core/shell particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), SQUID MPMS and rheometry. The morphological results showed titanium oxide nanorods with 100-200 nm length and 10-20 nm diameter coated on the surface of 200-300 nm Fe3O4 submicrospheres. Reaction time, the titanium source, the barium salt etc. have an influence on the morphology of core/shell particles. The core/shell particles can not only respond to an external magnetic field, but also to an electric field--a novel application of electrorheological fluid.

  19. Self-Assembly of Spinel Nanocrystals into Mesoporous Spheres as Bifunctionally Active Oxygen Reduction and Evolution Electrocatalysts.

    Science.gov (United States)

    Lee, Dong Un; Li, Jingde; Park, Moon Gyu; Seo, Min Ho; Ahn, Wook; Stadelmann, Ian; Ricardez-Sandoval, Luis; Chen, Zhongwei

    2017-05-22

    The present work introduces spinel oxide nanocrystals self-assembled into mesoporous spheres that are bifunctionally active towards catalyzing both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). The electrochemical evaluation reveals that (Ni,Co) 3 O 4 demonstrates a significantly positive-shifted ORR onset and half-wave potentials [-0.127 and -0.292 V vs. saturated calomel electrode (SCE), respectively], whereas Co 3 O 4 results in a negative-shifted OER potential (0.65 V vs. SCE) measured at 10 mA cm -2 . Based on the DFT analysis, the potential at which all oxygen intermediate reactions proceed spontaneously is the highest for (Ni,Co) 3 O 4 (U=0.66 eV) during ORR, whereas it is the lowest for Co 3 O 4 (U=2.09 eV) during OER. The high ORR activity of (Ni,Co) 3 O 4 is attributed to the enhanced electrical conductivity of the spinel lattice, and the high OER activity of Co 3 O 4 is attributed to relatively weak adsorption energy promoting rapid release of evolved oxygen. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Design, synthesis and evaluation of novel bifunctional tetrahydroxamate chelators for PET imaging of (89)Zr-labeled antibodies.

    Science.gov (United States)

    Rousseau, Julie; Zhang, Zhengxing; Dias, Gemma M; Zhang, Chengcheng; Colpo, Nadine; Bénard, François; Lin, Kuo-Shyan

    2017-02-15

    Two compact and symmetrical bifunctional tetrahydroxamate chelators, 1 and 2, were synthesized and evaluated for labeling antibodies with (89)Zr for imaging with positron emission tomography. Using 2,2'-iminodiacetamide as the backbone, four hydroxamate-containing moieties coupled to the diacetamide nitrogen were used for (89)Zr labeling, while a pendant connected to the amino group provided an isothiocyanate group for coupling to the antibody. Both 1- and 2-conjugated Trastuzumab were labeled with (89)Zr efficiently (>90% radiolabeling yield), and their (89)Zr-labeled products maintained comparable immunoreactivity to Trastuzumab. Compared to (89)Zr-labeled deferoxamine-conjugated Trastuzumab, (89)Zr-1- and (89)Zr-2-Trastuzumab showed faster demetalation in mouse plasma, and also displayed higher bone uptake in mice. Despite suboptimal stability of (89)Zr complexes of 1 and 2, our design strategy led to tetrahydroxamate chelators for efficient (89)Zr labeling, and could be potentially modified to provide novel chelators with improved stability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting

    Science.gov (United States)

    Wang, Haotian; Lee, Hyun-Wook; Deng, Yong; Lu, Zhiyi; Hsu, Po-Chun; Liu, Yayuan; Lin, Dingchang; Cui, Yi

    2015-01-01

    Developing earth-abundant, active and stable electrocatalysts which operate in the same electrolyte for water splitting, including oxygen evolution reaction and hydrogen evolution reaction, is important for many renewable energy conversion processes. Here we demonstrate the improvement of catalytic activity when transition metal oxide (iron, cobalt, nickel oxides and their mixed oxides) nanoparticles (∼20 nm) are electrochemically transformed into ultra-small diameter (2–5 nm) nanoparticles through lithium-induced conversion reactions. Different from most traditional chemical syntheses, this method maintains excellent electrical interconnection among nanoparticles and results in large surface areas and many catalytically active sites. We demonstrate that lithium-induced ultra-small NiFeOx nanoparticles are active bifunctional catalysts exhibiting high activity and stability for overall water splitting in base. We achieve 10 mA cm−2 water-splitting current at only 1.51 V for over 200 h without degradation in a two-electrode configuration and 1 M KOH, better than the combination of iridium and platinum as benchmark catalysts. PMID:26099250

  2. Electrochemical Oxidation of Chlorine-Doped Co(OH)2 Nanosheet Arrays on Carbon Cloth as a Bifunctional Oxygen Electrode.

    Science.gov (United States)

    Kou, Yue; Liu, Jie; Li, Yingbo; Qu, Shengxiang; Ma, Chao; Song, Zhishuang; Han, Xiaopeng; Deng, Yida; Hu, Wenbin; Zhong, Cheng

    2018-01-10

    The primary challenge of developing clean energy conversion/storage systems is to exploit an efficient bifunctional electrocatalyst both for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with low cost and good durability. Here, we synthesized chlorine-doped Co(OH)2 in situ grown on carbon cloth (Cl-doped Co(OH)2) as an integrated electrode by a facial electrodeposition method. The anodic potential was then applied to the Cl-doped Co(OH)2 in an alkaline solution to remove chlorine atoms (electro-oxidation (EO)/Cl-doped Co(OH)2), which can further enhance the electrocatalytic activity without any thermal treatment. EO/Cl-doped Co(OH)2 exhibits a better performance both for ORR and OER in terms of activity and durability because of the formation of a defective structure with a larger electrochemically active surface area after the electrochemical oxidation. This approach provides a new idea for introducing defects and developing active electrocatalyst.

  3. Dinuclear silylium-enolate bifunctional active species: remarkable activity and stereoselectivity toward polymerization of methacrylate and renewable methylene butyrolactone monomers.

    Science.gov (United States)

    Zhang, Yuetao; Gustafson, Laura O; Chen, Eugene Y-X

    2011-08-31

    Novel dinuclear silylium-enolate active species, consisting of an electrophilic silylium catalyst site and a nucleophilic silicon enolate initiating site that are covalently linked as single molecules, and their unique polymerization characteristics and kinetics are reported. Such unimolecular, bifunctional propagating species are conveniently generated from activation of ethyl- and oxo-bridged disilicon enolate (i.e., disilyl ketene acetal, di-SKA) compounds with [Ph(3)C][B(C(6)F(5))(4)]. Both the ethyl- and oxo-bridged dinuclear species are much more active for the polymerization of methyl methacrylate (MMA) than the mononuclear SKA-based active species, exhibiting an approximate rate enhancement by a factor of 12 and 44, respectively. The oxo-bridged silylium-enolate species is considerably more active and controlled than the ethyl-bridged one, with their differences being even more pronounced in polymerizing a renewable monomer, γ-methyl-α-methylene-γ-butyrolactone. The polymerization by the oxo-bridged silylium-enolate active species follows first-order kinetics in both monomer and silylium catalyst concentrations, indicating a unimolecular propagation mechanism which involves an intramolecular delivery of the polymeric enolate nucleophile to the monomer activated by the silylium ion electrophile being placed in proximity in the same catalyst molecule. Highly stereoregular poly(methyl methacrylate) (PMMA), with a syndiotacticity up to 92% rr, can be produced in quantitative yield using the oxo-bridged propagator at low temperature.

  4. [Effect of bifunctional IL2-GMCSF in promoting dendritic cell activation in vitro in simulated tumor-induced immune suppression].

    Science.gov (United States)

    Wen, Qian; Xiong, Wenjing; Liu, Sudong; Zhou, Chaoying; Ma, Li

    2015-08-01

    To test the effect of bifunctional molecule IL2-GMCSF in promoting the activation of dendritic cells (DCs) cultured in tumor conditioned medium. We prepared a tumor conditioned medium using mouse melanoma cell line B16F10 supplemented with IL2-GMCSF, GM-CSF, IL-2, or the combination of the latter two. After culturing mouse DC cell line DC2.4 in the conditioned medium for 24 h, the DCs were examined for phagocytosis, proliferation, maturation phenotype, cytokine secretion, and signal pathway activation. DC2.4 cells displayed characteristics of immature DCs. After cell culture in the conditioned medium, the cells showed enhanced phagocytosis but significantly suppressed cell proliferation activity. Culture in the conditioned medium also promoted DC cell maturation and secretion of macrophage-derived chemokine (MDC), but inhibited IL-12 secretion. Supplementation of the conditioned medium with IL2-GMCSF promoted phagocytosis, proliferation, maturation, and cytokine (including both IL-12 and MDC) secretion of DC2.4 cells. Compared with GM-CSF, IL2-GMCSF induced a higher level of NF-κB signal pathway activation but suppressed STAT3 activation. Compared with GM-CSF, IL2-GMCSF can better promote DC activation in the context of tumor-induced immune suppression, and thus shows potentials in anti-tumor therapy.

  5. Identification and overexpression of a bifunctional aldehyde/alcohol dehydrogenase responsible for ethanol production in Thermoanaerobacter mathranii.

    Science.gov (United States)

    Yao, Shuo; Mikkelsen, Marie Just

    2010-01-01

    Thermoanaerobacter mathranii contains four genes, adhA, adhB, bdhA and adhE, predicted to code for alcohol dehydrogenases involved in ethanol metabolism. These alcohol dehydrogenases were characterized as NADP(H)-dependent primary alcohol dehydrogenase (AdhA), secondary alcohol dehydrogenase (AdhB), butanol dehydrogenase (BdhA) and NAD(H)-dependent bifunctional aldehyde/alcohol dehydrogenase (AdhE), respectively. Here we observed that AdhE is an important enzyme responsible for ethanol production in T. mathranii based on the constructed adh knockout strains. An adhE knockout strain fails to produce ethanol as a fermentation product, while other adh knockout strains showed no significant difference from the wild type. Further analysis revealed that the ΔadhE strain was defective in aldehyde dehydrogenase activity, but still maintained alcohol dehydrogenase activity. This showed that AdhE is the major aldehyde dehydrogenase in the cell and functions predominantly in the acetyl-CoA reduction to acetaldehyde in the ethanol formation pathway. Finally, AdhE was conditionally expressed from a xylose-induced promoter in a recombinant strain (BG1E1) with a concomitant deletion of a lactate dehydrogenase. Overexpressions of AdhE in strain BG1E1 with xylose as a substrate facilitate the production of ethanol at an increased yield. Copyright © 2010 S. Karger AG, Basel.

  6. Mineralization of hetero bi-functional reactive dye in aqueous solution by Fenton and photo-Fenton reactions.

    Science.gov (United States)

    Torrades, Francesc; García-Hortal, José Antonio; García-Montaño, Julia

    2015-01-01

    This study focused on the advanced oxidation of the hetero bi-functional reactive dye Sumifix Supra Yellow 3RF (CI Reactive Yellow 145) using dark Fenton and photo-Fenton conditions in a lab-scale experiment. A 2(3) factorial design was used to evaluate the effects of the three key factors: temperature, Fe(II) and H2O2 concentrations, for a dye concentration of 250 mg L(-1) with chemical oxygen demand (COD) of 172 mg L(-1) O2 at pH=3. The response function was the COD reduction. This methodology lets us find the effects and interactions of the studied variables and their roles in the efficiency of the treatment process. In the optimization, the correlation coefficients for the model (R2) were 0.948 and 0.965 for Fenton and photo-Fenton treatments, respectively. Under optimized reaction conditions: pH=3, temperature=298 K, [H2O2]=11.765 mM and [Fe(II)]=1.075 mM; 60 min of treatment resulted in a 79% and 92.2% decrease in COD, for the dye taken as the model organic compound, after Fenton and photo-Fenton treatments, respectively.

  7. Triphenyl borate as a bi-functional additive to improve surface stability of Ni-rich cathode material

    Science.gov (United States)

    Yim, Taeeun; Jang, Seol Heui; Han, Young-Kyu

    2017-12-01

    Nickel-rich cathode material has received marked attention as an advanced cathode material, however, its inferior surface property limits the achievement of high performance in lithium-ion batteries. We propose the use of a bi-functional additive of triphenyl borate (TPB) for improvement of the safety and electrochemical performance of Ni-rich cathode materials. First, TPB removes residual lithium species from the Ni-rich cathode surface via chemical binding with anion part of residual lithium species, and effectively reduces swelling behavior of the cell. Second, TPB creates effective cathode-electrolyte interphase (CEI) layers on the electrode surface by an electrochemical reaction, and greatly enhances the surface stability of the nickel-rich cathode. This work demonstrate that a cell cycled with the TPB additive exhibits a remarkable retention of 88.6% at 60 °C after 100 cycles for an NCM721 cathode material. We suggest a working mechanism for TPB based on systematic analyses, including in-situ and ex-situ experiments.

  8. Bifunctional fluorescent benzimidazo[1,2-α]quinolines for Candida spp. biofilm detection and biocidal activity.

    Science.gov (United States)

    de Souza, Igor O P; Schrekker, Clarissa M L; Lopes, William; Orru, Romano V A; Hranjec, Marijana; Perin, Nataša; Machado, Michel; Oliveira, Luís F; Donato, Ricardo K; Stefani, Valter; Fuentefria, Alexandre M; Schrekker, Henri S

    2016-10-01

    Biofilms provide an ideal environment for protecting the microbial cells from damage caused by humoral and cellular immune system components, promoting resistance, infections and increasing mortality and morbidity of patients in health facilities. In an attempt to provide an innovative solution for preventing contamination in hospital environments, this study evaluated nine structural complementary fluorescent benzimidazo[1,2-α]quinolines as bifunctional agents that both detect and have biocidal activity against yeast biofilms on stainless steel surfaces. The benzimidazoles' staining capability was determined by a fluorescence microscopy study and spraying the substance on yeast biofilm contaminated stainless steel surfaces. Furthermore, their in vitro human leukocyte cytotoxicity was evaluated with trypan blue and their biocidal activity was determined as the minimum inhibitory concentration against Candida tropicalis, C. albicans and C. parapsilosis strains. Moreover, scanning electron micrographs were recorded to study the biocidal activity. This resulted in the identification of 7, which presents all the desired characteristics (such as solubility) and capabilities (staining and biocide activity against all tested biofilm forming yeast strains) at the same time. As such, benzimidazole 7 has the potential to guarantee the use of disinfected medical and surgical instruments in clinical and surgical procedures, consequently, contributing to an increased safety for patients. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. DT-Diaphorase as a Bifunctional Enzyme Label That Allows Rapid Enzymatic Amplification and Electrochemical Redox Cycling.

    Science.gov (United States)

    Kang, Cheolho; Kang, Juyeon; Lee, Nam-Sihk; Yoon, Young Ho; Yang, Haesik

    2017-08-01

    The most common enzyme labels in enzyme-linked immunosorbent assays are alkaline phosphatase and horseradish peroxidase, which, however, have some limitations for use in electrochemical immunosensors. This Article reports that the small and thermostable DT-diaphorase (DT-D) and electrochemically inactive 4-nitroso-1-naphthol (4-NO-1-N) can be used as a bifunctional enzyme label and a rapidly reacting substrate, respectively, for electrochemical immunosensors. This enzyme-substrate combination allows high signal amplification via rapid enzymatic amplification and electrochemical redox cycling. DT-D can convert an electrochemically inactive nitroso or nitro compound into an electrochemically active amine compound, which can then be involved in electrochemical-chemical (EC) and electrochemical-enzymatic (EN) redox cycling. Six nitroso and nitro compounds are tested in terms of signal-to-background ratio. Among them, 4-NO-1-N exhibits the highest signal-to-background ratio. The electrochemical immunosensor using DT-D and 4-NO-1-N detects parathyroid hormone (PTH) in phosphate-buffered saline containing bovine serum albumin over a wide range of concentrations with a low detection limit of 2 pg/mL. When the PTH concentration in clinical serum samples is measured using the developed immunosensor, the calculated concentrations are in good agreement with the concentrations obtained using a commercial instrument. Thus, the use of DT-D as an enzyme label is highly promising for sensitive electrochemical detection and point-of-care testing.

  10. Aromatic Halogenation by Using Bifunctional Flavin Reductase-Halogenase Fusion Enzymes.

    Science.gov (United States)

    Andorfer, Mary C; Belsare, Ketaki D; Girlich, Anna M; Lewis, Jared C

    2017-09-06

    The remarkable site selectivity and broad substrate scope of flavin-dependent halogenases (FDHs) has led to much interest in their potential as biocatalysts. Multiple engineering efforts have demonstrated that FDHs can be tuned for non-native substrate scope and site selectivity. FDHs have also proven useful as in vivo biocatalysts and have been successfully incorporated into biosynthetic pathways to build new chlorinated aromatic compounds in several heterologous organisms. In both cases, reduced flavin cofactor, usually supplied by a separate flavin reductase (FR), is required. Herein, we report functional synthetic, fused FDH-FR proteins containing various FDHs and FRs joined by different linkers. We show that FDH-FR fusion proteins can increase product titers compared to the individual components for in vivo biocatalysis in Escherichia coli. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Comparison of the octadentate bifunctional chelator DFO*-pPhe-NCS and the clinically used hexadentate bifunctional chelator DFO-pPhe-NCS for {sup 89}Zr-immuno-PET

    Energy Technology Data Exchange (ETDEWEB)

    Vugts, Danielle J.; Klaver, Chris; Sewing, Claudia; Poot, Alex J.; Adamzek, Kevin; Visser, Gerard W.M.; Dongen, Guus A.M.S. van [VU University Medical Center, Department of Radiology and Nuclear Medicine, Amsterdam (Netherlands); Huegli, Seraina; Mari, Cristina; Gasser, Gilles [University of Zurich, Department of Chemistry, Zurich (Switzerland); Valverde, Ibai E. [University of Basel Hospital, Division of Radiopharmaceutical Chemistry, Basel (Switzerland); Mindt, Thomas L. [Institute of Pharmaceutical Sciences, ETH Zurich, Zurich (Switzerland); General Hospital of Vienna, Ludwig Boltzmann Institute for Applied Diagnostics, Vienna (Austria)

    2017-02-15

    All clinical {sup 89}Zr-immuno-PET studies are currently performed with the chelator desferrioxamine (DFO). This chelator provides hexadentate coordination to zirconium, leaving two coordination sites available for coordination with, e.g., water molecules, which are relatively labile ligands. The unsaturated coordination of DFO to zirconium has been suggested to result in impaired stability of the complex in vivo and consequently in unwanted bone uptake of {sup 89}Zr. Aiming at clinical improvements, we report here on a bifunctional isothiocyanate variant of the octadentate chelator DFO* and the in vitro and in vivo comparison of its {sup 89}Zr-DFO*-mAb complex with {sup 89}Zr-DFO-mAb. The bifunctional chelator DFO*-pPhe-NCS was prepared from previously reported DFO* and p-phenylenediisothiocyanate. Subsequently, trastuzumab was conjugated with either DFO*-pPhe-NCS or commercial DFO-pPhe-NCS and radiolabeled with Zr-89 according to published procedures. In vitro stability experiments were carried out in saline, a histidine/sucrose buffer, and blood serum. The in vivo performance of the chelators was compared in N87 tumor-bearing mice by biodistribution studies and PET imaging. In 0.9 % NaCl {sup 89}Zr-DFO*-trastuzumab was more stable than {sup 89}Zr-DFO-trastuzumab; after 72 h incubation at 2-8 C 95 % and 58 % intact tracer were left, respectively, while in a histidine-sucrose buffer no difference was observed, both products were ≥ 92 % intact. In vivo uptake at 144 h post injection (p.i.) in tumors, blood, and most normal organs was similar for both conjugates, except for skin, liver, spleen, ileum, and bone. Tumor uptake was 32.59 ± 11.95 and 29.06 ± 8.66 % ID/g for {sup 89}Zr-DFO*-trastuzumab and {sup 89}Zr-DFO-trastuzumab, respectively. The bone uptake was significantly lower for {sup 89}Zr-DFO*-trastuzumab compared to {sup 89}Zr-DFO-trastuzumab. At 144 h p.i. for {sup 89}Zr-DFO*-trastuzumab and {sup 89}Zr-DFO-trastuzumab, the uptake in sternum was 0.92

  12. The Golgi localized bifunctional UDP-rhamnose/UDP-galactose transporter family of Arabidopsis

    DEFF Research Database (Denmark)

    Rautengarten, Carsten; Ebert, Berit; Moreno, Ignacio

    2014-01-01

    Delivery of nucleotide sugar substrates into the Golgi apparatus and endoplasmic reticulum for processes such as cell wall biosynthesis and protein glycosylation is critical for plant growth and development. Plant genomes encode large families of uncharacterized nucleotide sugar transporters......-of-function and overexpression lines for two of these transporters identified biochemical alterations supporting their roles in the biosynthesis of Rha- and Gal-containing polysaccharides. Thus, cell wall polysaccharide biosynthesis in the Golgi apparatus of plants is likely also regulated by substrate transport mechanisms....

  13. CO2capture performance of bi-functional activated bleaching earth modified with basic-alcoholic solution and functionalization with monoethanolamine: isotherms, kinetics and thermodynamics.

    Science.gov (United States)

    Pongstabodee, Sangobtip; Pornaroontham, Phuwadej; Pintuyothin, Nuthapol; Pootrakulchote, Nuttapol; Thouchprasitchai, Nutthavich

    2016-10-01

    CO 2 capture performance of bifunctional activated bleaching earth (ABE) was investigated at atmospheric pressure. The sorbents were characterized by means of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Caron-Hydrogen-Nitrogen analysis (CHN), Fourier transform infrared (FT-IR) and thermal gravimetric analysis (TGA). The CO 2 capacity was enhanced via basic-modification and monoethanolamine (MEA) loading of the ABE sorbent to obtain a bifunctional surface property. Here, basic-modified calcined ABE with a 30wt.% MEA loading (SAB-30) showed the highest CO 2 capture capacity, but this was decreased with excess MEA loading (>30wt.%). At a 10% (V/V) initial CO 2 concentration feed, the maximum capacity of SAB-30 increased from 2.71mmol/g at 30°C (without adding moisture to the feed) to 3.3mmol/g at 50°C when adding 10% (V/V) moisture to the feed. Increasing the moisture concentration further reduced the maximum CO 2 capacity due to the blocking effect of the excess moisture on the sorbent surface. However, SAB-30 could completely capture CO 2 even in a 100% (V/V) initial CO 2 concentration feed. A maximum CO 2 capacity of 5.7mmol/g for SAB-30 was achieved at 30°C. Varying the ratio of sorbent weight to total flow rate of the gas stream had no discernible effect on the equilibrium CO 2 capture capacity. Avrami's equation and Toth's isotherm model provided a good fitting for the data and suggested the presence of more than one reaction pathway in the CO 2 capture process and the heterogeneous adsorption surface of SAB-30. Thermodynamics studies revealed that CO 2 capture on the bifunctional SAB-30 is feasible, spontaneous and exothermic in nature. Copyright © 2016. Published by Elsevier B.V.

  14. Evolution of Conifer Diterpene Synthases: Diterpene Resin Acid Biosynthesis in Lodgepole Pine and Jack Pine Involves Monofunctional and Bifunctional Diterpene Synthases1[W][OA

    Science.gov (United States)

    Hall, Dawn E.; Zerbe, Philipp; Jancsik, Sharon; Quesada, Alfonso Lara; Dullat, Harpreet; Madilao, Lina L.; Yuen, Macaire; Bohlmann, Jörg

    2013-01-01

    Diterpene resin acids (DRAs) are major components of pine (Pinus spp.) oleoresin. They play critical roles in conifer defense against insects and pathogens and as a renewable resource for industrial bioproducts. The core structures of DRAs are formed in secondary (i.e. specialized) metabolism via cycloisomerization of geranylgeranyl diphosphate (GGPP) by diterpene synthases (diTPSs). Previously described gymnosperm diTPSs of DRA biosynthesis are bifunctional enzymes that catalyze the initial bicyclization of GGPP followed by rearrangement of a (+)-copalyl diphosphate intermediate at two discrete class II and class I active sites. In contrast, similar diterpenes of gibberellin primary (i.e. general) metabolism are produced by the consecutive activity of two monofunctional class II and class I diTPSs. Using high-throughput transcriptome sequencing, we discovered 11 diTPS from jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta). Three of these were orthologous to known conifer bifunctional levopimaradiene/abietadiene synthases. Surprisingly, two sets of orthologous PbdiTPSs and PcdiTPSs were monofunctional class I enzymes that lacked functional class II active sites and converted (+)-copalyl diphosphate, but not GGPP, into isopimaradiene and pimaradiene as major products. Diterpene profiles and transcriptome sequences of lodgepole pine and jack pine are consistent with roles for these diTPSs in DRA biosynthesis. The monofunctional class I diTPSs of DRA biosynthesis form a new clade within the gymnosperm-specific TPS-d3 subfamily that evolved from bifunctional diTPS rather than monofunctional enzymes (TPS-c and TPS-e) of gibberellin metabolism. Homology modeling suggested alterations in the class I active site that may have contributed to their functional specialization relative to other conifer diTPSs. PMID:23370714

  15. A bi-functional xyloglucan galactosyltransferase is an indispensable salt stress tolerance determinant in arabidop

    KAUST Repository

    Li, Wenbo

    2013-07-01

    Salinity is an abiotic stress that substantially limits crop production worldwide. To identify salt stress tolerance determinants, we screened for Arabidopsis mutants that are hypersensitive to salt stress and designated these mutants as short root in salt medium (rsa). One of these mutants, rsa3-1, is hypersensitive to NaCl and LiCl but not to CsCl or to general osmotic stress. Reactive oxygen species (ROS) over-accumulate in rsa3-1 plants under salt stress. Gene expression profiling with Affymetrix microarray analysis revealed that RSA3 controls expression of many genes including genes encoding proteins for ROS detoxification under salt stress. Map-based cloning showed that RSA3 encodes a xyloglucan galactosyltransferase, which is allelic to a gene previously named MUR3/KAM1. The RSA3/ MUR3/KAM1-encoded xylogluscan galactosyltransferase regulates actin microfilament organization (and thereby contributes to endomembrane distribution) and is also involved in cell wall biosynthesis. In rsa3-1, actin cannot assemble and form bundles as it does in the wild-type but instead aggregates in the cytoplasm. Furthermore, addition of phalloidin, which prevents actin depolymerization, can rescue salt hypersensitivity of rsa3-1. Together, these results suggest that RSA3/MUR3/KAM1 along with other cell wall-associated proteins plays a critical role in salt stress tolerance by maintaining the proper organization of actin microfilaments in order to minimize damage caused by excessive ROS. © 2013 The Author.

  16. Selective transformation of carbon dioxide into lower olefins with a bifunctional catalyst composed of ZnGa2O4 and SAPO-34.

    Science.gov (United States)

    Liu, Xiaoliang; Wang, Mengheng; Zhou, Cheng; Zhou, Wei; Cheng, Kang; Kang, Jincan; Zhang, Qinghong; Deng, Weiping; Wang, Ye

    2017-12-06

    A bifunctional catalyst composed of ZnGa2O4 with a spinel structure and molecular sieve SAPO-34 catalyses the direct conversion of CO2 to C2-C4 olefins with a selectivity of 86% and a CO2 conversion of 13% at 370 °C. The oxygen vacancies on ZnGa2O4 surfaces are responsible for CO2 activation, forming a methanol intermediate, which is then converted into C2-C4 olefins in SAPO-34.

  17. Production of propylene from 1-butene on highly active "bi-functional single active site" catalyst: Tungsten carbene-hydride supported on alumina

    KAUST Repository

    Mazoyer, Etienne

    2011-12-02

    1-Butene is transformed in a continuous flow reactor over tungsten hydrides precursor W-H/Al2O3, 1, giving a promising yield into propylene at 150 °C and different pressures. Tungsten carbene-hydride single active site operates as a "bi-functional catalyst" through 1-butene isomerization on W-hydride and 1-butene/2-butenes cross-metathesis on W-carbene. This active moiety is generated in situ at the initiation steps by insertion of 1-butene on tungsten hydrides precursor W-H/Al2O3, 1 followed by α-H and β-H abstraction. © 2011 American Chemical Society.

  18. Amide-Phosphonium Salt as Bifunctional Phase Transfer Catalyst for Asymmetric 1,6-Addition of Malonate Esters to para-Quinone Methides.

    Science.gov (United States)

    Ge, Luo; Lu, Xuehe; Cheng, Cang; Chen, Jie; Cao, Weiguo; Wu, Xiaoyu; Zhao, Gang

    2016-10-07

    Asymmetric 1,6-addition of malonates to para-quinone methides has been developed by using amide-phosphonium salts derived from easily available chiral α-amino acids as bifunctional phase transfer catalysts. Stabilized para-quinone methides with various substituents on the phenyl ring were reacted with diphenyl malonates to give functionalized diaryl methines in excellent yields and high to excellent ee's. Furthermore, to show the utility of this methodology, a gram scale synthesis of an 1,6-addition adduct and its further elaboration into the key intermediate for synthesis of GPR40 agonists were also described.

  19. A bifunctional aminoglycoside acetyltransferase/phosphotransferase conferring tobramycin resistance provides an efficient selectable marker for plastid transformation.

    Science.gov (United States)

    Tabatabaei, Iman; Ruf, Stephanie; Bock, Ralph

    2017-02-01

    A new selectable marker gene for stable transformation of the plastid genome was developed that is similarly efficient as the aadA, and produces no background of spontaneous resistance mutants. More than 25 years after its development for Chlamydomonas and tobacco, the transformation of the chloroplast genome still represents a challenging technology that is available only in a handful of species. The vast majority of chloroplast transformation experiments conducted thus far have relied on a single selectable marker gene, the spectinomycin resistance gene aadA. Although a few alternative markers have been reported, the aadA has remained unrivalled in efficiency and is, therefore, nearly exclusively used. The development of new marker genes for plastid transformation is of crucial importance to all efforts towards extending the species range of the technology as well as to those applications in basic research, biotechnology and synthetic biology that involve the multistep engineering of plastid genomes. Here, we have tested a bifunctional resistance gene for its suitability as a selectable marker for chloroplast transformation. The bacterial enzyme aminoglycoside acetyltransferase(6')-Ie/aminoglycoside phosphotransferase(2″)-Ia possesses an N-terminal acetyltransferase domain and a C-terminal phosphotransferase domain that can act synergistically and detoxify aminoglycoside antibiotics highly efficiently. We report that, in combination with selection for resistance to the aminoglycoside tobramycin, the aac(6')-Ie/aph(2″)-Ia gene represents an efficient marker for plastid transformation in that it produces similar numbers of transplastomic lines as the spectinomycin resistance gene aadA. Importantly, no spontaneous antibiotic resistance mutants appear under tobramycin selection.

  20. Novel MOF-Derived Co@N-C Bifunctional Catalysts for Highly Efficient Zn-Air Batteries and Water Splitting.

    Science.gov (United States)

    Zhang, Mingdao; Dai, Quanbin; Zheng, Hegen; Chen, Mindong; Dai, Liming

    2018-01-19

    Metal-organic frameworks (MOFs) and MOF-derived materials have recently attracted considerable interest as alternatives to noble-metal electrocatalysts. Herein, the rational design and synthesis of a new class of Co@N-C materials (C-MOF-C2-T) from a pair of enantiotopic chiral 3D MOFs by pyrolysis at temperature T is reported. The newly developed C-MOF-C2-900 with a unique 3D hierarchical rodlike structure, consisting of homogeneously distributed cobalt nanoparticles encapsulated by partially graphitized N-doped carbon rings along the rod length, exhibits higher electrocatalytic activities for oxygen reduction and oxygen evolution reactions (ORR and OER) than that of commercial Pt/C and RuO 2 , respectively. Primary Zn-air batteries based on C-MOF-900 for the oxygen reduction reaction (ORR) operated at a discharge potential of 1.30 V with a specific capacity of 741 mA h g Zn -1 under 10 mA cm -2 . Rechargeable Zn-air batteries based on C-MOF-C2-900 as an ORR and OER bifunctional catalyst exhibit initial charge and discharge potentials at 1.81 and 1.28 V (2 mA cm -2 ), along with an excellent cycling stability with no increase in polarization even after 120 h - outperform their counterparts based on noble-metal-based air electrodes. The resultant rechargeable Zn-air batteries are used to efficiently power electrochemical water-splitting systems, demonstrating promising potential as integrated green energy systems for practical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. A Novel N-Acetylglutamate Synthase Architecture Revealed by the Crystal Structure of the Bifunctional Enzyme from Maricaulis maris

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Dashuang; Li, Yongdong; Cabrera-Luque, Juan; Jin, Zhongmin; Yu, Xiaolin; Zhao, Gengxiang; Haskins, Nantaporn; Allewell, Norma M.; Tuchman, Mendel (Maryland); (GWU); (Georgia)

    2012-05-24

    Novel bifunctional N-acetylglutamate synthase/kinases (NAGS/K) that catalyze the first two steps of arginine biosynthesis and are homologous to vertebrate N-acetylglutamate synthase (NAGS), an essential cofactor-producing enzyme in the urea cycle, were identified in Maricaulis maris and several other bacteria. Arginine is an allosteric inhibitor of NAGS but not NAGK activity. The crystal structure of M. maris NAGS/K (mmNAGS/K) at 2.7 {angstrom} resolution indicates that it is a tetramer, in contrast to the hexameric structure of Neisseria gonorrhoeae NAGS. The quaternary structure of crystalline NAGS/K from Xanthomonas campestris (xcNAGS/K) is similar, and cross-linking experiments indicate that both mmNAGS/K and xcNAGS are tetramers in solution. Each subunit has an amino acid kinase (AAK) domain, which is likely responsible for N-acetylglutamate kinase (NAGK) activity and has a putative arginine binding site, and an N-acetyltransferase (NAT) domain that contains the putative NAGS active site. These structures and sequence comparisons suggest that the linker residue 291 may determine whether arginine acts as an allosteric inhibitor or activator in homologous enzymes in microorganisms and vertebrates. In addition, the angle of rotation between AAK and NAT domains varies among crystal forms and subunits within the tetramer. A rotation of 26{sup o} is sufficient to close the predicted AcCoA binding site, thus reducing enzymatic activity. Since mmNAGS/K has the highest degree of sequence homology to vertebrate NAGS of NAGS and NAGK enzymes whose structures have been determined, the mmNAGS/K structure was used to develop a structural model of human NAGS that is fully consistent with the functional effects of the 14 missense mutations that were identified in NAGS-deficient patients.

  2. The role of the methyltransferase domain of bifunctional restriction enzyme RM.BpuSI in cleavage activity.

    Directory of Open Access Journals (Sweden)

    Arthur Sarrade-Loucheur

    Full Text Available Restriction enzyme (REase RM.BpuSI can be described as a Type IIS/C/G REase for its cleavage site outside of the recognition sequence (Type IIS, bifunctional polypeptide possessing both methyltransferase (MTase and endonuclease activities (Type IIC and endonuclease activity stimulated by S-adenosyl-L-methionine (SAM (Type IIG. The stimulatory effect of SAM on cleavage activity presents a major paradox: a co-factor of the MTase activity that renders the substrate unsusceptible to cleavage enhances the cleavage activity. Here we show that the RM.BpuSI MTase activity modifies both cleavage substrate and product only when they are unmethylated. The MTase activity is, however, much lower than that of M1.BpuSI and is thought not to be the major MTase for host DNA protection. SAM and sinefungin (SIN increase the Vmax of the RM.BpuSI cleavage activity with a proportional change in Km, suggesting the presence of an energetically more favorable pathway is taken. We further showed that RM.BpuSI undergoes substantial conformational changes in the presence of Ca(2+, SIN, cleavage substrate and/or product. Distinct conformers are inferred as the pre-cleavage/cleavage state (in the presence of Ca(2+, substrate or both and MTase state (in the presence of SIN and substrate, SIN and product or product alone. Interestingly, RM.BpuSI adopts a unique conformation when only SIN is present. This SIN-bound state is inferred as a branch point for cleavage and MTase activity and an intermediate to an energetically favorable pathway for cleavage, probably through increasing the binding affinity of the substrate to the enzyme under cleavage conditions. Mutation of a SAM-binding residue resulted in altered conformational changes in the presence of substrate or Ca(2+ and eliminated cleavage activity. The present study underscores the role of the MTase domain as facilitator of efficient cleavage activity for RM.BpuSI.

  3. Single-Site Active Iron-Based Bifunctional Oxygen Catalyst for a Compressible and Rechargeable Zinc-Air Battery.

    Science.gov (United States)

    Ma, Longtao; Chen, Shengmei; Pei, Zengxia; Huang, Yan; Liang, Guojin; Mo, Funian; Yang, Qi; Su, Jun; Gao, Yihua; Zapien, Juan Antonio; Zhi, Chunyi

    2018-02-27

    The exploitation of a high-efficient, low-cost, and stable non-noble-metal-based catalyst with oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) simultaneously, as air electrode material for a rechargeable zinc-air battery is significantly crucial. Meanwhile, the compressible flexibility of a battery is the prerequisite of wearable or/and portable electronics. Herein, we present a strategy via single-site dispersion of an Fe-N x species on a two-dimensional (2D) highly graphitic porous nitrogen-doped carbon layer to implement superior catalytic activity toward ORR/OER (with a half-wave potential of 0.86 V for ORR and an overpotential of 390 mV at 10 mA·cm -2 for OER) in an alkaline medium. Furthermore, an elastic polyacrylamide hydrogel based electrolyte with the capability to retain great elasticity even under a highly corrosive alkaline environment is utilized to develop a solid-state compressible and rechargeable zinc-air battery. The creatively developed battery has a low charge-discharge voltage gap (0.78 V at 5 mA·cm -2 ) and large power density (118 mW·cm -2 ). It could be compressed up to 54% strain and bent up to 90° without charge/discharge performance and output power degradation. Our results reveal that single-site dispersion of catalytic active sites on a porous support for a bifunctional oxygen catalyst as cathode integrating a specially designed elastic electrolyte is a feasible strategy for fabricating efficient compressible and rechargeable zinc-air batteries, which could enlighten the design and development of other functional electronic devices.

  4. The bifunctional plant receptor, OsCERK1, regulates both chitin-triggered immunity and arbuscular mycorrhizal symbiosis in rice.

    Science.gov (United States)

    Miyata, Kana; Kozaki, Toshinori; Kouzai, Yusuke; Ozawa, Kenjirou; Ishii, Kazuo; Asamizu, Erika; Okabe, Yoshihiro; Umehara, Yosuke; Miyamoto, Ayano; Kobae, Yoshihiro; Akiyama, Kohki; Kaku, Hanae; Nishizawa, Yoko; Shibuya, Naoto; Nakagawa, Tomomi

    2014-11-01

    Plants are constantly exposed to threats from pathogenic microbes and thus developed an innate immune system to protect themselves. On the other hand, many plants also have the ability to establish endosymbiosis with beneficial microbes such as arbuscular mycorrhizal (AM) fungi or rhizobial bacteria, which improves the growth of host plants. How plants evolved these systems managing such opposite plant-microbe interactions is unclear. We show here that knockout (KO) mutants of OsCERK1, a rice receptor kinase essential for chitin signaling, were impaired not only for chitin-triggered defense responses but also for AM symbiosis, indicating the bifunctionality of OsCERK1 in defense and symbiosis. On the other hand, a KO mutant of OsCEBiP, which forms a receptor complex with OsCERK1 and is essential for chitin-triggered immunity, established mycorrhizal symbiosis normally. Therefore, OsCERK1 but not chitin-triggered immunity is required for AM symbiosis. Furthermore, experiments with chimeric receptors showed that the kinase domains of OsCERK1 and homologs from non-leguminous, mycorrhizal plants could trigger nodulation signaling in legume-rhizobium interactions as the kinase domain of Nod factor receptor1 (NFR1), which is essential for triggering the nodulation program in leguminous plants, did. Because leguminous plants are believed to have developed the rhizobial symbiosis on the basis of AM symbiosis, our results suggest that the symbiotic function of ancestral CERK1 in AM symbiosis enabled the molecular evolution to leguminous NFR1 and resulted in the establishment of legume-rhizobia symbiosis. These results also suggest that OsCERK1 and homologs serve as a molecular switch that activates defense or symbiotic responses depending on the infecting microbes. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  5. Hydro-isomerization of n-hexane on bi-functional catalyst: Effect of total and hydrogen partial pressures

    Science.gov (United States)

    Thoa, Dao Thi Kim; Loc, Luu Cam

    2017-09-01

    The effect of both total pressure and hydrogen partial pressure during n-hexane hydro-isomerization over platinum impregnated on HZSM-5 was studied. n-Hexane hydro-isomerization was conducted at atmospheric pressure and 0.7 MPa to observe the influence of total pressure. In order to see the effect of hydrogen partial pressure, the reaction was taken place at different partial pressure of hydrogen varied from 307 hPa to 718 hPa by dilution with nitrogen to keep the total pressure at 0.1 MPa. Physico-chemical characteristics of catalyst were determined by the methods of nitrogen physi-sorption BET, SEM, XRD, TEM, NH3-TPD, TPR, and Hydrogen Pulse Chemi-sorption. Activity of catalyst in the hydro-isomerization of n-hexane was studied in a micro-flow reactor in the temperature range of 225-325 °C; the molar ratio H2/ hydrocarbon: 5.92, concentration of n-hexane: 9.2 mol.%, GHSV 2698 h-1. The obtained catalyst expressed high acid density, good reducing property, high metal dispersion, and good balance between metallic and acidic sites. It is excellent contact for n-hexane hydro-isomerization. At 250 °C, n-hexane conversion and selectivity were as high as 59-76 % and 85-99 %, respectively. It was found that catalytic activity was promoted either by total pressure or hydrogen partial pressure. At total pressure of 0.7 MPa while hydrogen partial pressure of 718 hPa, catalyst produced 63 RON liquid product containing friendly environmental iso-paraffins which is superior blending stock for green gasoline. Hydrogen did not only preserve catalyst actives by depressing hydrocracking and removing coke precursors but also facilitated hydride transfer step in the bi-functional bi-molecular mechanism.

  6. Bifunctional role of leucine 300 of firefly luciferase in structural rigidity.

    Science.gov (United States)

    Yousefi, Farzad; Ataei, Farangis; Mortazavi, Mojtaba; Hosseinkhani, Saman

    2017-08-01

    Firefly luciferase is susceptible to thermal inactivation, thereby its intracellular half-life decreased. Previous reports indicated that L(300)R mutation (LRR mutant) in E(354)R/Arg(356) double mutant (ERR mutant) from Lampyris turkestanicus luciferase has increased its thermal stability and rigidity through induction of some ionic bonds with Asp 270 and 271. Disruption of the deduced ionic bonds in an ultra-rigid mutant of firefly luciferase did not reverse the flexibility of the protein. In this study, we investigated the effects of this residue to find the truth behind an extraordinary increase in thermal stability and rigidity of luciferase after replacement of leucine 300 by arginine based on previous reports. For this purpose, L(300)R, L(300)K and L(300)E mutations were performed to compare the effects of these mutations on the native firefly luciferase. In spite of increase of intrinsic fluorescence of the mutants a slight increase in thermostability and retention of kinetic properties was observed. Based on our results, we can conclude that L(300)R mutation in LRR mutant accompanying with alteration in a flexible loop (352-359) increased thermostability and rigidity of luciferase. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Vascular calcification and aortic fibrosis: a bifunctional role for osteopontin in diabetic arteriosclerosis.

    Science.gov (United States)

    Shao, Jian-Su; Sierra, Oscar L; Cohen, Richard; Mecham, Robert P; Kovacs, Attila; Wang, James; Distelhorst, Kathryn; Behrmann, Abraham; Halstead, Linda R; Towler, Dwight A

    2011-08-01

    Calcification and fibrosis reduce vascular compliance in arteriosclerosis. To better understand the role of osteopontin (OPN), a multifunctional protein upregulated in diabetic arteries, we evaluated contributions of OPN in male low-density lipoprotein receptor (LDLR)-/- mice fed a high-fat diet. OPN had no impact on high-fat diet-induced hyperglycemia, dyslipidemia, or body composition. However, OPN-/-;LDLR-/- mice exhibited an altered time-course of aortic calcium accrual-reduced during initiation but increased with progression-versus OPN+/+;LDLR-/- controls. Collagen accumulation, chondroid metaplasia, and mural thickness were increased in aortas of OPN-/-;LDLR-/- mice. Aortic compliance was concomitantly reduced. Vascular reexpression of OPN (SM22-OPN transgene) reduced aortic Col2A1 and medial chondroid metaplasia but did not affect atherosclerotic calcification, Col1A1 expression, collagen accumulation, or arterial stiffness. Dosing with the proinflammatory OPN fragment SVVYGLR upregulated aortic Wnt and osteogenic gene expression, increased aortic β-catenin, and restored early-phase aortic calcification in OPN-/-;LDLR-/- mice. OPN exerts stage-specific roles in arteriosclerosis in LDLR-/- mice. Actions phenocopied by the OPN metabolite SVVYGLR promote osteogenic calcification processes with disease initiation. OPN limits vascular chondroid metaplasia, endochondral mineralization, and collagen accumulation with progression. Complete deficiency yields a net increase in arteriosclerotic disease, reducing aortic compliance and conduit vessel function in LDLR-/- mice.

  8. Application of meta- and para- phenylenediamine as enhanced oxime ligation catalysts for protein labeling, PEGylation, immobilization and release

    Science.gov (United States)

    Mahmoodi, Mohammad M.; Rashidian, Mohammad; Zhang, Yi; Distefano, Mark D.

    2015-01-01

    Meta- and para- phenylenediamines have recently been shown to catalyze oxime and hydrazone ligation reactions at rates much faster than aniline, a commonly used catalyst. Here, it is demonstrated how these new catalysts can be used in a generally applicable procedure for fluorescent labeling, PEGylation, immobilization and release of aldehyde and ketone functionalized proteins. The chemical orthogonality of phenylenediamine-catalyzed oxime ligation versus copper catalyzed click reaction has also been harnessed for simultaneous dual labeling of bifunctional proteins containing both aldehyde and alkyne groups in high yield. PMID:25640893

  9. Plasma-Assisted Synthesis of Self-Supporting Porous CoNPs@C Nanosheet as Efficient and Stable Bifunctional Electrocatalysts for Overall Water Splitting.

    Science.gov (United States)

    Jin, Qiuyan; Ren, Bowen; Li, Dongqi; Cui, Hao; Wang, Chengxin

    2017-09-20

    The utilization of a highly active and robust bifunctional catalyst for simultaneously producing H2 and O2 is still a major challenging issue, which is vital for improving the efficiency of overall water splitting. Herein, we employ a novel plasma-assisted strategy to rapidly and conveniently synthesize the three-dimensional (3D) porous composite nanosheets assembled on monodispersed Co nanoparticles encapsulated in a carbon framework (CoNPs@C) on a carbon cloth. Such a novel 3D hierarchical porous nanosheet improves the exposure and accessibility of active sites as well as ensures high electroconductibility. Moreover, the coating of a few graphene layers on the surface of catalysts favors improvement of the catalytic activity. Benefited from these multiple merits, the CoNPs@C composite nanosheets enable a low overpotential of 153 mV at -10 mA cm-2 for hydrogen evolution reaction. Furthermore, they are also capable of catalyzing the oxygen evolution reaction with high efficiency to achieve current density of 10 mA cm-2 at the overpotential of 270 mV. Remarkably, when assembled as an alkaline water electrolyzer, the bifunctional CoNPs@C composite nanosheets can afford a water-splitting current density of 10 mA cm-2 at a cell voltage of 1.65 V.

  10. Development of a Bifunctional Aptamer Targeting the Transferrin Receptor and Epithelial Cell Adhesion Molecule (EpCAM) for the Treatment of Brain Cancer Metastases.

    Science.gov (United States)

    Macdonald, Joanna; Henri, Justin; Goodman, Lynda; Xiang, Dongxi; Duan, Wei; Shigdar, Sarah

    2017-04-19

    The treatment of brain disorders is greatly hindered by the presence of the blood-brain barrier, which restricts the overwhelming majority of small molecules from entering the brain. A novel approach by which to overcome this barrier is to target receptor mediated transport mechanisms present on the endothelial cell membranes. Therefore, we fused an aptamer that binds to epithelial cell adhesion molecule-expressing cancer cells to an aptamer targeting the transferrin receptor. This generated a proof of concept bifunctional aptamer that can overcome the blood-brain barrier and potentially specifically target brain disorders. The initial fusion of the two sequences enhanced the binding affinity of both aptamers while maintaining specificity. Additionally, mutations were introduced into both binding loops to determine their effect on aptamer specificity. The ability of the aptamer to transcytose the blood-brain barrier was then confirmed in vivo following a 1 nmol injection. This study has shown that through the fusion of two aptamer sequences, a bifunctional aptamer can be generated that has the potential to be developed for the specific treatment of brain disorders.

  11. Bifunctional compounds eliciting anti-inflammatory and anti-cholinesterase activity as potential treatment of nerve and blister chemical agents poisoning.

    Science.gov (United States)

    Amitai, Gabi; Adani, Rachel; Fishbein, Eliezer; Meshulam, Haim; Laish, Ido; Dachir, Schlomit

    2005-12-15

    Studies cited by Cowan et al. [J. Appl. Toxicol. 23, 177 (2003)] indicate existence of inflammatory and cholinergic pathways in both nerve agents and sulfur mustard (HD) injury. Increase in AChE synthesis and neurite extension was noted after exposure to HD [K.W. Lanks et al., Exp. Cell Res. 355 (1975)]. Moreover, anti-inflammatory drugs reduce the dermal, respiratory and ocular damage caused by exposure to HD. On the other hand, recent studies have noted the involvement of neuro-inflammatory processes during exposure to the nerve agents sarin or soman [Cowan et al., 2003]. The use of various anti-inflammatory drugs in addition to the classical antidotal drugs (e.g. atropine and oximes) caused decrease in certain toxic symptoms and inflammation-induced brain damage. Our new bifunctional drugs (Scheme 1) are based on CNS-permeable molecular combination of pseudo-reversible AChE inhibitor (pyridostigmine, PYR) coupled via a hydrophobic spacer (octyl or decyl hydrocarbon chain) to a non-steroidal anti-inflammatory drug (NSAID) such as Ibuprofen or Diclofenac (Scheme 1). This study evaluates the efficacy of certain bifunctional compounds against HD and soman poisoning in mice in vivo.

  12. Novel molecularly imprinted polymers based on multiwalled carbon nanotubes with bifunctional monomers for solid-phase extraction of rhein from the root of kiwi fruit.

    Science.gov (United States)

    Chen, Xing; Zhang, Zhaohui; Yang, Xiao; Liu, Yunan; Li, Jiaxing; Peng, Mijun; Yao, Shouzhuo

    2012-09-01

    A novel molecularly imprinted polymers based on multiwalled carbon nanotubes synthesized by precipitate polymerization was applied as a selective sorbent for separation and determination of rhein (4,5-dihydroxyanthraquinone-2-carboxylic acid) from the root of kiwi fruit samples coupled with high performance liquid chromatography (HPLC). The molecularly imprinted polymers were prepared with methacrylic acid and 4-vinylpyridine as bifunctional monomers. The chemical structure of the molecularly imprinted polymers was characterized by Fourier transform infrared spectrometer. The equilibrium rebinding experiment and competitive adsorption experiment showed that these imprinted polymers exhibited good adsorption ability toward rhein. The Langmuir adsorption equilibrium constant, K(m) , and theoretical maximum adsorption capacity, Q(m) , were estimated to be 0.43 and 6.77 mg g(-1) , respectively. Compared with molecularly imprinted polymers prepared with methacrylic acid or 4-vinylpyridine solely, the molecularly imprinted polymers synthesized with bifunctional monomers showed enhanced molecular imprinting effect and higher adsorption capacity for the template rhein. The performances of the molecularly imprinted polymers utilized as solid phase extraction sorbent were investigated in detail. The molecularly imprinted polymers prepared by the method proposed in this work could successfully apply to extraction and determination of rhein from the root of kiwi fruit samples coupled with HPLC. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. One-Pot Process for Hydrodeoxygenation of Lignin to Alkanes Using Ru-Based Bimetallic and Bifunctional Catalysts Supported on Zeolite Y

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongliang [Department of Biological Systems Engineering, Washington State University, Richland WA 99354 USA; Ruan, Hao [Department of Biological Systems Engineering, Washington State University, Richland WA 99354 USA; Feng, Maoqi [Chemistry & Chemical Engineering Division, Southwest Research Institute, San Antonio TX 78238 USA; Qin, Yuling [Department of Biological Systems Engineering, Washington State University, Richland WA 99354 USA; Job, Heather [Pacific Northwest National Laboratory, 902 Battelle Blvd Richland WA 99354 USA; Luo, Langli [Environmental Molecular Sciences Laboratory, 3335 Q Ave Richland WA 99354 USA; Wang, Chongmin [Environmental Molecular Sciences Laboratory, 3335 Q Ave Richland WA 99354 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, 3335 Q Ave Richland WA 99354 USA; Kuhn, Erik [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO. 80401 USA; Chen, Xiaowen [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO. 80401 USA; Tucker, Melvin P. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO. 80401 USA; Yang, Bin [Department of Biological Systems Engineering, Washington State University, Richland WA 99354 USA

    2017-03-16

    The synthesis of high-efficiency and low-cost multifunctional catalysts for hydrodeoxygenation (HDO) of waste lignin into advanced biofuels is crucial for enhancing current biorefinery processes. Inexpensive transition metals, including Fe, Ni, Cu, Zn, were severally co-loaded with Ru on HY zeolite to form bimetallic and bifunctional catalysts. These catalysts were subsequently tested for HDO conversion of softwood lignin and several lignin model compounds. Results indicated that the inexpensive earth abundant metals could modulate the hydrogenolysis activity of Ru and decrease the yield of low molecular weight gaseous side-products. Among all the prepared catalysts, Ru-Cu/HY showed the best HDO performance, giving the highest selectivity to hydrocarbon products. The improved catalytic performance of Ru-Cu/HY was probably due to the following three factors: (1) high total and strong acid sites, (2) good dispersion of metal species and limited segregation, (3) high adsorption capacity for polar fractions, including hydroxyl groups and ether bonds. Moreover, all the bifunctional catalysts were proven to be superior over the combination catalysts of Ru/Al2O3 and HY zeolite, and this could be attributed to the “intimacy criterion”. The practical use of the designed catalysts would be promising in lignin valorization.

  14. Co3O4 nanoparticle-modified MnO2 nanotube bifunctional oxygen cathode catalysts for rechargeable zinc-air batteries

    Science.gov (United States)

    Du, Guojun; Liu, Xiaogang; Zong, Yun; Hor, T. S. Andy; Yu, Aishui; Liu, Zhaolin

    2013-05-01

    We report the preparation of MnO2 nanotubes functionalized with Co3O4 nanoparticles and their use as bifunctional air cathode catalysts for oxygen reduction reaction and oxygen evolution reaction in rechargeable zinc-air batteries. These hybrid MnO2/Co3O4 nanomaterials exhibit enhanced catalytic reactivity toward oxygen evolution reaction under alkaline conditions compared with that in the presence of MnO2 nanotubes or Co3O4 nanoparticles alone.We report the preparation of MnO2 nanotubes functionalized with Co3O4 nanoparticles and their use as bifunctional air cathode catalysts for oxygen reduction reaction and oxygen evolution reaction in rechargeable zinc-air batteries. These hybrid MnO2/Co3O4 nanomaterials exhibit enhanced catalytic reactivity toward oxygen evolution reaction under alkaline conditions compared with that in the presence of MnO2 nanotubes or Co3O4 nanoparticles alone. Electronic supplementary information (ESI) available: Zinc-air cell device, XPS survey scan and power density of the cell. See DOI: 10.1039/c3nr00300k

  15. Platinum(II) as Bifunctional Linker in Antibody-Drug Conjugate Formation: Coupling of a 4-Nitrobenzo-2-oxa-1,3-diazole Fluorophore to Trastuzumab as a Model

    NARCIS (Netherlands)

    Waalboer, D.C.J.; Muns, J.A.; Sijbrandi, N.J.; Schasfoort, R.B.M.; Haselberg, R.; Somsen, G.W.; Houthoff, H.J.; van Dongen, G.A.M.S.

    2015-01-01

    The potential of platinum(II) as a bifunctional linker in the coordination of small molecules, such as imaging agents or (cytotoxic) drugs, to monoclonal antibodies (mAbs) was investigated with a 4-nitrobenzo-2-oxa-1,3-diazole (NBD) fluorophore and trastuzumab (Herceptin™) as a model antibody. The

  16. Ethanol synthesis and water gas shift over bifunctional sulfide catalysts. Final technical progress report, September 12, 1991--December 11, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Klier, K.; Herman, R.G.; Deemer, M.; Richards-Babb, M.; Carr, T.

    1995-07-01

    The objective of this research was to investigate sulfur-resistant catalysts for the conversion of synthesis gas having H{sub 2}/CO {le} 1 into C{sub 1}--C{sub 4} alcohols, especially ethanol, by a highly selective and efficient pathway, while also promoting the water gas shift reaction (WGSR). The catalysts chosen are bifunctional, base-hydrogenation, sulfur-tolerant transition metal sulfides with heavy alkali, e.g. Cs{sup +}, promoter dispersed on their surfaces. The modes of activation of H{sub 2} and CO on MoS{sub 2} and alkali-doped MoS{sub 2} were considered, and computational analyses of the thermodynamic stability of transition metal sulfides and of the electronic structure of these sulfide catalysts were carried out. In the preparation of the cesium-promoted MoS{sub 2} catalysts, a variety of preparation methods using CsOOCH were examined. In all cases, doping with CsOOCH led to a lost of surface area. The undoped molybdenum disulfide catalyst only produced hydrocarbons. Cs-doped MoS{sub 2} catalysts all produced linear alcohols, along with smaller amounts of hydrocarbons. With a 20 wt% CsOOCH/MoS{sub 2} catalyst, temperature, pressure, and flow rate dependences of the synthesis reactions were investigated in the presence and absence of H{sub 2}S in the H{sub 2}/CO = 1/1 synthesis gas during short term testing experiments. It was shown that with a carefully prepared 10 wt% CsOOCH/MoS{sub 2} catalyst, reproducible and high alcohol synthesis activity could be obtained. For example, at 295 C with H{sub 2}/CO = 1 synthesis gas at 8.3 MPa and with GHSV = 7,760 l/kg cat/hr, the total alcohol space time yield was ca 300 g/kg cat/hr (accompanied with a hydrocarbon space time yield of ca 60 g/kg cat/hr). Over a testing period of ca 130 hr, no net deactivation of the catalyst was observed. 90 refs., 82 figs., 14 tabs.

  17. One-pot facile electrospinning construct of flexible Janus nanofibers with tunable and enhanced magnetism–photoluminescence bifunctionality

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liyan [Jilin Jianzhu University, Key Laboratory of Building Energy-Saving Technology Engineering, College of Materials Science and Engineering (China); Dong, Xiangting, E-mail: dongxiangting888@163.com [Changchun University of Science and Technology, Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province (China); Gai, Guangqing, E-mail: gaigq@163.com; Zhao, Li [Jilin Jianzhu University, Key Laboratory of Building Energy-Saving Technology Engineering, College of Materials Science and Engineering (China); Xu, Shuzhi [Jilin Business and Technology College, School of Biotechnology Engineering (China); Xiao, Xinfu [Jilin Jianzhu University, Key Laboratory of Building Energy-Saving Technology Engineering, College of Materials Science and Engineering (China)

    2015-02-15

    A novel nanostructure of flexible Janus nanofibers with tunable and enhanced magnetism–photoluminescence difunctionality has been successfully fabricated by one-pot electrospinning using specially designed parallel spinneret. Europium complex Eu(BA){sub 3}phen (BA = benzoic acid, phen = 1,10-phenanthroline), terbium complex Tb(BA){sub 3}phen, and Fe{sub 3}O{sub 4} nanoparticles (NPs) were, respectively, incorporated into polyvinyl pyrrolidone (PVP) and electrospun into Janus nanofibers. The morphology, structure, and property of the Janus nanofibers were investigated in detail by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, fluorescence spectroscopy, and vibrating sample magnetometry. The average diameter of the Janus nanofibers is about ca. 300 nm. Every Janus nanofiber is composed of one nanofiber with different performances on two sides, one side is composed of Fe{sub 3}O{sub 4} NPs and PVP, and the other side consists of [Eu(BA){sub 3}phen + Tb(BA){sub 3}phen] and PVP. This novel nanostructures can effectively isolate Eu(BA){sub 3}phen and Tb(BA){sub 3}phen from Fe{sub 3}O{sub 4} NPs so that the exciting light and emitting light in the [Eu(BA){sub 3}phen + Tb(BA){sub 3}phen]/PVP domain will almost not be affected by Fe{sub 3}O{sub 4} NPs. The Janus nanofibers possess higher fluorescent intensity owing to their special nanostructure compared with non-Janus composite nanofiber with the same compositions. Moreover, the Janus nanofibers have multicolored and color-tunable photoluminescence, the emitting color could be tuned in a wide color range of red–yellow–green by adjusting the molar ratio of Eu(BA){sub 3}phen to Tb(BA){sub 3}phen under the excitation of 274-nm single-wavelength ultraviolet light, and the magnetism also could be tuned by changing the amounts of Fe{sub 3}O{sub 4} NPs. The new type Janus nanofibers with tunable and enhanced magnetism–photoluminescence bifunctionality have

  18. Syntheses, structures, and magnetic properties of inorganic-organic hybrid cobalt(II) phosphites containing bifunctional ligands.

    Science.gov (United States)

    Fan, Jian; Yee, Gordon T; Wang, Guangbin; Hanson, Brian E

    2006-01-23

    Seven new cobalt(II) phosphites, [Co(HPO(3))(C(14)H(14)N(4))(H(2)O)(2)].2H(2)O (1), [Co(HPO(3))(C(22)H(18)N(4))].H(2)O (2), [Co(2)(HPO(3))(2)(C(22)H(18)N(4))(2)H(2)O].H(2)O (3), [Co(2)(HPO(3))(2)(C(12)H(10)N(4))(1.5)H(2)O].1.5H(2)O (4), [Co(HPO(3))(C(14)H(14)N(4))(0.5)].H(2)O (5), [Co(HPO(3))(C(18)H(16)N(4))(0.5)] (6), and [Co(HPO(3))(C(18)H(16)N(4))(0.5)] (7) were synthesized in the presence of 1,2-bis(imidazol-1-ylmethyl)benzene (L1), 1,4-bis(benzimidazol-1-ylmethyl)benzene (L2), 1,3-bis(benzimidazol-1-ylmethyl)benzene (L3), 1,4-bis(1-imidazolyl)benzene (L4), 1,4-bis(imidazol-1-ylmethyl)benzene (L5), 1,4-bis(imidazol-1-ylmethyl)naphthalene (L6), and 1,5-bis(imidazol-1-ylmethyl)naphthalene (L7), respectively, and their structures were determined by X-ray crystallography. Compound 1 is a molecular compound in which two cobalt(II) ions are held together by double mu-O linkages. The inorganic framework of compounds 2 and 3 are composed of vertex-shared CoO(2)N(2)/CoO(3)N(2) and HPO(3) polyhedra that form four rings; these are further linked by an organic ligand to generate 2D sheets. Compounds 4 and 5 both have 1D inorganic structures, with the bifunctional ligands connected to each side of the ladder by coordination bonds to give 2D hybrid sheets. A 3D organically pillared hybrid framework is observed in 6 and 7. In 6, the stacking of the interlayer pillars gives rise to a small hydrophobic channel that extends through the entire structure parallel to the sheets. The temperature-dependent magnetic susceptibility measurements of these compounds show weak interactions between the metal centers, mediated through the mu-O and/or O-P-O linkages.

  19. Detection of amyloid plaques targeted by bifunctional USPIO in Alzheimer's disease transgenic mice using magnetic resonance microimaging.

    Directory of Open Access Journals (Sweden)

    Youssef Zaim Wadghiri

    Full Text Available Amyloid plaques are a key pathological hallmark of Alzheimer's disease (AD. The detection of amyloid plaques in the brain is important for the diagnosis of AD, as well as for following potential amyloid targeting therapeutic interventions. Our group has developed several contrast agents to detect amyloid plaques in vivo using magnetic resonance microimaging (µMRI in AD transgenic mice, where we used mannitol to enhance blood brain barrier (BBB permeability. In the present study, we used bifunctional ultrasmall superparamagnetic iron oxide (USPIO nanoparticles, chemically coupled with Aβ1-42 peptide to image amyloid plaque deposition in the mouse brain. We coupled the nanoparticles to polyethylene glycol (PEG in order to improve BBB permeability. These USPIO-PEG-Aβ1-42 nanoparticles were injected intravenously in AD model transgenic mice followed by initial in vivo and subsequent ex vivo μMRI. A 3D gradient multi-echo sequence was used for imaging with a 100 µm isotropic resolution. The amyloid plaques detected by T2*-weighted μMRI were confirmed with matched histological sections. The region of interest-based quantitative measurement of T2* values obtained from the in vivo μMRI showed contrast injected AD Tg mice had significantly reduced T2* values compared to wild-type mice. In addition, the ex vivo scans were examined with voxel-based analysis (VBA using statistical parametric mapping (SPM for comparison of USPIO-PEG-Aβ1-42 injected AD transgenic and USPIO alone injected AD transgenic mice. The regional differences seen by VBA in the USPIO-PEG-Aβ1-42 injected AD transgenic correlated with the amyloid plaque distribution histologically. Our results indicate that USPIO-PEG-Aβ1-42 can be used for amyloid plaque detection in vivo by intravenous injection without the need to co-inject an agent which increases permeability of the BBB. This technique could aid the development of novel amyloid targeting drugs by allowing therapeutic effects

  20. Bifunctional sensor of pentachlorophenol and copper ions based on nanostructured hybrid films of humic acid and exfoliated layered double hydroxide via a facile layer-by-layer assembly

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Shuang; Peng, Dinghua [Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079 (China); Hu, Xianluo [State Key Laboratory of Material Processing and Die and Mould Technology, College of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China); Gong, Jingming, E-mail: jmgong@mail.ccnu.edu.cn [Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079 (China)

    2013-06-27

    Graphical abstract: -- Highlights: •A new highly sensitive bifunctional electrochemical sensor developed. •As-prepared sensor fabricated by alternate assembly of HA and exfoliated LDH nanosheets. •Such a newly designed sensor combining the individual properties of HA and LDH nanosheets. •Simultaneous determination of pentachlorophenol and copper ions achieved. •Practical applications demonstrated in water samples. -- Abstract: A new, highly sensitive bifunctional electrochemical sensor for the simultaneous determination of pentachlorophenol (PCP) and copper ions (Cu{sup 2+}) has been developed, where organic–inorganic hybrid ultrathin films were fabricated by alternate assembly of humic acid (HA) and exfoliated Mg–Al-layered double hydroxide (LDH) nanosheets onto ITO substrates via a layer-by-layer (LBL) approach. The multilayer films were then characterized by means of UV–vis spectrometry, scanning electron microscopy (SEM), and atomic force microscope (AFM). These films were found to have a relatively smooth surface with almost equal amounts of HA incorporated in each cycle. Its electrochemical performance was systematically investigated. Our results demonstrate that such a newly designed (LDH/HA){sub n} multilayer films, combining the individual properties of HA (dual recognition ability for organic herbicides and metal ions) together with LDH nanosheets (a rigid inorganic matrix), can be applied to the simultaneous analysis of PCP and Cu(II) without interference from each other. The LBL assembled nanoarchitectures were further investigated by X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR), which provides insight for bifunctional sensing behavior. Under the optimized conditions, the detection limit was found to be as low as 0.4 nM PCP, well below the guideline value of PCP in drinking water (3.7 nM) set by the United States Environmental Protection Agency (U.S. EPA), and 2.0 nM Cu{sup 2+}, much below the guideline value (2

  1. Ultrathin Co3O4 nanofilm as an efficient bifunctional catalyst for oxygen evolution and reduction reaction in rechargeable zinc-air batteries.

    Science.gov (United States)

    He, Yu; Zhang, Jinfeng; He, Guowei; Han, Xiaopeng; Zheng, Xuerong; Zhong, Cheng; Hu, Wenbin; Deng, Yida

    2017-06-29

    Two-dimensional (2D) nanocatalysts with a large specific surface area and efficient charge conductivity are promising candidates for catalyzing the sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which are at the heart of various electrochemical energy conversion and storage technologies. Here, we report the synthesis of an ultrathin Co3O4 nanofilm with a thickness of nearly 1.8 nm via a surfactant- and template-free facile hydrothermal route. The proposed synthesis strategy can be extended to the preparation of 2D NixCo3-xO4 and FexCo3-xO4 nanostructures. The synthesized Co3O4 nanofilm exhibited bifunctional activity that was superior to that of the counterpart Co3O4 nanoparticles, including a lower overpotential and higher reduction and evolution current densities, and demonstrated faster catalytic kinetics over the 2D nanofilm surface. In comparison with precious metal-based catalysts, to achieve an OER current density of 40 mA cm-2 the overpotential of the nanofilm (461 mV) was lower than that of RuO2 (526 mV), whereas the ORR on the nanofilm proceeded via a dominant 4e- transfer mechanism, which is similar to that of commercial carbon-supported Pt (Pt/C). The Co3O4 nanofilm enabled the assembly of rechargeable Zn-air batteries with a lower overpotential (0.72 V), higher round-trip efficiency (62.7%), and a longer cycle lifetime (175 cycles). The remarkable bifunctional activity contributes to an increase in the number of electrochemically active sites, a large interfacial contact area with the electrolyte, and the enrichment of Co3+ ions on the surface, which facilitates the adsorption and activation of oxygen-containing species. This study should shed light on the future development of new electroactive materials with optimized 2D nanostructures to enhance the overall bifunctional ORR/OER performance of rechargeable metal-air batteries.

  2. Bi-functional modified-phosphate catalyzed the synthesis of α-α′-(EE)-bis(benzylidene)-cycloalkanones: Microwave versus conventional-heating

    KAUST Repository

    Solhy, Abderrahim

    2011-02-01

    The impregnation of hydroxyapatite (HAP) by NaNO3 leads to a modified-hydroxyapatite which has a bi-functional acid-base property. Sodium-modified-hydroxyapatite (Na-HAP) efficiently catalyzed the cross-aldol condensation of arylaldehydes and cycloketones to afford α-α′- (EE)-bis(benzylidene)-cycloalkanones in good yields under microwave irradiation. Moreover, the methodology described in this paper provides a very easy and efficient synthesis carried out in water as the greenest available solvent under conventional heating. A comparison study between these two different modes of heating was investigated. The catalyst was easily recovered and efficiently re-used. © 2010 Elsevier B.V.

  3. Stability of bifunctional air electrodes depending on the CO{sub 2} content in the air and study of different CO{sub 2} filter materials

    Energy Technology Data Exchange (ETDEWEB)

    Holzer, F.; Mueller, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Drillet, J.F. [Fachhochschule Mannheim, D-68167 Mannheim (Germany); Kallis, T. [DaimlerChrysler AG, D-68299 Mannheim (Germany)

    2001-03-01

    The stability of bifunctional oxygen electrodes used in electrically rechargeable zinc/air batteries was investigated in air/air cells as a function of CO{sub 2} concentration in the feed gas supplied to the oxygen reducing electrode. With pure oxygen as the feed gas, a limiting lifetime of about 2500 h was first attained at the oxygen evolving electrode. However, when CO{sub 2} concentrations of 400 to 10'000 ppm were present in the feed gas, the lifetime of the oxygen reducing electrode was drastically shortened due to electrode degradation by carbonate precipitation inside the pores of its gas diffusion layer. Several alkaline CO{sub 2}-adsorbing materials were tested for their filtering efficiency. It was found that the filter capacity strongly depends on the relative humidity of the feed gas. (author)

  4. Facile synthesis of chiral spirooxindole-based isotetronic acids and 5-1H-pyrrol-2-ones through cascade reactions with bifunctional organocatalysts.

    Science.gov (United States)

    Guo, Wengang; Wang, Xu; Zhang, Boyu; Shen, Shuai; Zhou, Xin; Wang, Peng; Liu, Yan; Li, Can

    2014-07-07

    Unprecedented organocatalyzed asymmetric cascade reactions have been developed for the facile synthesis of chiral spirooxindole-based isotetronic acids and 5-1H-pyrrol-2-ones.The asymmetric 1,2-addition reactions of α-ketoesters to isatins and imines by using an acid-base bifunctional 6'-OH cinchona alkaloid catalyst, followed by cyclization and enolization of the resulting adducts, gave chiral spiroisotetronic acids and 5-1H-pyrrol-2-ones, respectively, in excellent optical purities (up to 98 % ee). FT-IR analysis supported the existence of hydrogen-bonding interaction between the 6'-OH group of the cinchona catalyst and an isatin carbonyl group, an interaction that might be crucial for catalyst activity and stereocontrol. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Type II Anion Relay Chemistry: Exploiting Bifunctional Weinreb Amide Linchpins for the One-Pot Synthesis of Differentiated 1,3-Diketones, Pyrans, and Spiroketals.

    Science.gov (United States)

    Farrell, Mark; Melillo, Bruno; Smith, Amos B

    2016-01-04

    The design, synthesis, and validation of new highly effective bifunctional linchpins for type II anion relay chemistry (ARC) has been achieved. The mechanistically novel negative-charge migration that comprises the Brook rearrangement is now initiated by a stabilized tetrahedral intermediate, which is generated by nucleophilic addition to a Weinreb amide, rather than by a simple oxyanion that is generated from an epoxide. As a result, the linchpin preserves the carbonyl functionality in the ARC adducts, thus permitting access to functionally complex systems in a single flask without the need for further chemical manipulations. This tactic was validated with the one-pot preparation of monoprotected 1,3-diketones as well as pyran and spiroketal scaffolds, depending on the choice of nucleophile, electrophile, and work-up conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Synthesis of bifunctional catalysts Al-SBA-15-NH{sub 2} with high aluminum content and the catalytic application for different one-pot reactions

    Energy Technology Data Exchange (ETDEWEB)

    Wang Chunhua; Shang Fanpeng; Yu Xiaofang [Jilin University, Changchun (China); Guan Jingqi, E-mail: guanjq@jlu.edu.cn [Jilin University, Changchun (China); Kan Qiubin, E-mail: qkan@mail.jlu.edu.cn [Jilin University, Changchun (China)

    2012-07-01

    Acid-base bifunctional mesoporous catalysts Al-SBA-15-NH{sub 2} containing high content of Al and organic amine functional groups have been synthesized through the 'pH-adjusting' method. The materials were characterized by X-ray diffraction (XRD), scanning electron micrographs (SEM), transmission electron micrographs (TEM), Fourier-transform infrared spectroscopy (FTIR), IR spectra of pyridine adsorption, NH{sub 3}-TPD and elemental analysis. Catalytic results showed that 6-Al-SBA-15-NH{sub 2} (Si/Al = 6 mol%) was more active than 10-Al-SBA-15-NH{sub 2} (Si/Al = 10 mol%) in one-pot deacetalization-Knoevenagel and deacetalization-nitroaldol (Henry) reactions.

  7. Cuboid Ni2P as a Bifunctional Catalyst for Efficient Hydrogen Generation from Hydrolysis of Ammonia Borane and Electrocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Du, Yeshuang; Liu, Chao; Cheng, Gongzhen; Luo, Wei

    2017-11-16

    The design of high-performance catalysts for hydrogen generation is highly desirable for the upcoming hydrogen economy. Herein, we report the colloidal synthesis of nanocuboid Ni 2 P by the thermal decomposition of nickel chloride hexahydrate (NiCl 2 ⋅6 H 2 O) and trioctylphosphine. The obtained nanocuboid Ni 2 P was characterized by using powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma atomic emission spectroscopy. For the first time, the as-synthesized nanocuboid Ni 2 P is used as a bifunctional catalyst for hydrogen generation from the hydrolysis of ammonia borane and electrocatalytic hydrogen evolution. Owing to the strong synergistic electronic effect between Ni and P, the as-synthesized Ni 2 P exhibits catalytic performance that is superior to its counterpart without P doping. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Efficient Water Electrolysis Using Ni2P as a Bifunctional Catalyst: Unveiling the Oxygen Evolution Catalytic Properties of Ni2P.

    Science.gov (United States)

    Stern, Lucas-Alexandre; Hu, Xile

    2016-01-01

    The excellent bifunctional catalytic activity of nickel phosphide (Ni2P) for water splitting is reported. Ni2P, an active hydrogen evolving catalyst, is shown to be highly active for oxygen evolution. Only 290 mV of overpotential is required to generate a current density of 10 mA cm(-2) in 1 M KOH. Under oxygen evolving conditions, Ni2P undergoes structural modification to form a Ni2P/NiOx core-shell assembly, the catalytic active species. Ni2P is applied on both electrodes of an alkaline electrolyser and a current density of 10 mA cm(-2) is generated at 1.63 V.

  9. Unleashing the Power and Energy of LiFePO4-Based Redox Flow Lithium Battery with a Bifunctional Redox Mediator.

    Science.gov (United States)

    Zhu, Yun Guang; Du, Yonghua; Jia, Chuankun; Zhou, Mingyue; Fan, Li; Wang, Xingzhu; Wang, Qing

    2017-05-10

    Redox flow batteries, despite great operation flexibility and scalability for large-scale energy storage, suffer from low energy density and relatively high cost as compared to the state-of-the-art Li-ion batteries. Here we report a redox flow lithium battery, which operates via the redox targeting reactions of LiFePO4 with a bifunctional redox mediator, 2,3,5,6-tetramethyl-p-phenylenediamine, and presents superb energy density as the Li-ion battery and system flexibility as the redox flow battery. The battery has achieved a tank energy density as high as 1023 Wh/L, power density of 61 mW/cm2, and voltage efficiency of 91%. Operando X-ray absorption near-edge structure measurements were conducted to monitor the evolution of LiFePO4, which provides insightful information on the redox targeting process, critical to the device operation and optimization.

  10. Bifunctional Sensing Mechanism of SnO2-ZnO Composite Nanofibers for Drastically Enhancing the Sensing Behavior in H2 Gas.

    Science.gov (United States)

    Katoch, Akash; Kim, Jae-Hun; Kwon, Yong Jung; Kim, Hyoun Woo; Kim, Sang Sub

    2015-06-03

    SnO2-ZnO composite nanofibers fabricated using an electrospinning method exhibited exceptional hydrogen (H2) sensing behavior. The existence of tetragonal SnO2 and hexagonal ZnO nanograins was confirmed by an analysis of the crystalline phase of the composite nanofibers. A bifunctional sensing mechanism of the composite nanofibers was proposed in which the combined effects of SnO2-SnO2 homointerfaces and ZnO-SnO2 heterointerfaces contributed to an improvement in the H2 sensing characteristics. The sensing process with respect to SnO2-ZnO heterojunctions is associated not only with the high barrier at the junctions, but also the semiconductor-to-metallic transition on the surface of the ZnO nanograins upon the introduction of H2 gas.

  11. Hierarchical nanostructured NiCo2O4 as an efficient bifunctional non-precious metal catalyst for rechargeable zinc-air batteries

    Science.gov (United States)

    Prabu, Moni; Ketpang, Kriangsak; Shanmugam, Sangaraju

    2014-02-01

    A nickel-doped cobalt oxide spinel structure is a promising non-precious metal electrocatalyst for oxygen evolution and oxygen reduction in rechargeable metal-air batteries and water electrolyzers operating with alkaline electrolytes. One dimensional NiCo2O4 (NCO) nanostructures were prepared by using a simple electrospinning technique with two different metal precursors (metal nitrate/PAN and metal acetylacetonate/PAN). The effect of precursor concentration on the morphologies was investigated. Single-phase, NCO with an average diameter of 100 nm, porous interconnected fibrous morphology was revealed by FESEM and FETEM analysis. The hierarchical nanostructured 1D-spinel NiCo2O4 materials showed a remarkable electrocatalytic activity towards oxygen reduction and evolution in an aqueous alkaline medium. The extraordinary bi-functional catalytic activity towards both ORR and OER was observed by the low over potential (0.84 V), which is better than that of noble metal catalysts [Pt/C (1.16 V), Ru/C (1.01 V) and Ir/C (0.92 V)], making them promising cathode materials for metal-air batteries. Furthermore, the rechargeable zinc-air battery with NCO-A1 as a bifunctional electrocatalyst displays high activity and stability during battery discharge, charge, and cycling processes.A nickel-doped cobalt oxide spinel structure is a promising non-precious metal electrocatalyst for oxygen evolution and oxygen reduction in rechargeable metal-air batteries and water electrolyzers operating with alkaline electrolytes. One dimensional NiCo2O4 (NCO) nanostructures were prepared by using a simple electrospinning technique with two different metal precursors (metal nitrate/PAN and metal acetylacetonate/PAN). The effect of precursor concentration on the morphologies was investigated. Single-phase, NCO with an average diameter of 100 nm, porous interconnected fibrous morphology was revealed by FESEM and FETEM analysis. The hierarchical nanostructured 1D-spinel NiCo2O4 materials showed a

  12. Active Salt/Silica-Templated 2D Mesoporous FeCo-Nx-Carbon as Bifunctional Oxygen Electrodes for Zinc-Air Batteries.

    Science.gov (United States)

    Li, Shuang; Cheng, Chong; Zhao, Xiaojia; Schmidt, Johannes; Thomas, Arne

    2018-02-12

    Two types of templates, an active metal salt and silica nanoparticles, are used concurrently to achieve the facile synthesis of hierarchical meso/microporous FeCo-N x -carbon nanosheets (meso/micro-FeCo-N x -CN) with highly dispersed metal sites. The resulting meso/micro-FeCo-N x -CN shows high and reversible oxygen electrocatalytic performances for both ORR and OER, thus having potential for applications in rechargeable Zn-air battery. Our approach creates a new pathway to fabricate 2D meso/microporous structured carbon architectures for bifunctional oxygen electrodes in rechargeable Zn-air battery as well as opens avenues to the scale-up production of rationally designed heteroatom-doped catalytic materials for a broad range of applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Synthesis of Bifunctional Fe3O4@SiO2-Ag Magnetic-Plasmonic Nanoparticles by an Ultrasound Assisted Chemical Method

    Science.gov (United States)

    Chu, Dung Tien; Sai, Doanh Cong; Luu, Quynh Manh; Tran, Hong Thi; Quach, Truong Duy; Kim, Dong Hyun; Nguyen, Nam Hoang

    2017-06-01

    Bifunctional magnetic-plasmonic nanoparticles (NPs)—Fe3O4@SiO2-Ag were successfully synthesized by an ultrasound assisted chemical method. Silver ions were absorbed and then reduced by sodium borohydride on the surface of 3-aminopropyltriethoxysilane (APTES) functionalized silica-coated magnetic NPs, then they were reduced under the influence of a 200 W ultrasonic wave for 60 min. When the amount of precursor silver ions increased, the relative intensity of diffraction peaks of silver crystals in all samples increased with the atomic ratio of silver/iron increasing from 0.208 to 0.455 and saturation magnetization ( M s) decreasing from 44.68 emu/g to 34.74 emu/g. The NPs have superparamagnetic properties and strong surface plasmon absorption at 420 nm, which make these particles promising for biomedical applications.

  14. Asymmetric Michael addition reactions of 3-substituted benzofuran-2(3H)-ones to nitroolefins catalyzed by a bifunctional tertiary-amine thiourea.

    Science.gov (United States)

    Li, Xin; Xue, Xiao-Song; Liu, Cong; Wang, Bin; Tan, Bo-Xuan; Jin, Jia-Lu; Zhang, Yue-Yan; Dong, Nan; Cheng, Jin-Pei

    2012-01-14

    The current work reports an organocatalytic strategy for the asymmetric catalysis of chiral benzofuran-2(3H)-ones bearing 3-position all-carbon quaternary stereocenters. Accordingly, highly enantioselective Michael addition reactions of 3-substituted benzofuran-2(3H)-ones to nitroolefins have been developed by utilizing a bifunctional tertiary-amine thiourea catalyst. The reactions accommodate a number of nitroolefins and 3-substituted benzofuran-2(3H)-ones to give the desired chiral benzofuran-2(3H)-one products with moderate to excellent yields (up to 98%) and moderate to very good selectivities (up to 19 : 1 dr and up to 91% ee). Theoretical calculations using the DFT method on the origin of the stereoselectivity were conducted. The effect of the nitroolefin substituent position on the stereoselectivity of the Michael addition reaction was also theoretically rationalized.

  15. Biochemical characterization of the bifunctional enzyme dihydrofolate reductase-thymidylate synthase from Leishmania (Viannia) and its evaluation as a drug target.

    Science.gov (United States)

    Osorio, Edison; Aguilera, Carolina; Naranjo, Nelson; Marín, Marcel; Muskus, Carlos

    2013-01-01

    Dihydrofolate reductase (DHFR) has been used successfully as a drug target in the area of anti-bacterial, anti-cancer and anti-malarial therapy. Although this bifunctional enzyme is also a potential drug target for treatment of leishmaniasis, there have been no reports on its efficacy against Leishmania (Viannia) species. The gene encoding the bifunctional DHFR and thymidylate synthase (TS) of Le. (V.) braziliensis was isolated and expressed in E. coli. The enzyme was purified and characterized. The inhibitory effects of antifolates and four aporphine alkaloids on its activity were evaluated. The full-length gene consists of a 1560-bp open reading frame encoding a 58 kDa translated peptide containing DHFR and TS domains linked together in a single polypeptide chain. The recombinant DHFR-TS enzyme revealed Km and Vmax values of 55.35 ± 4.02 µ M (mean ± SE) and 0.02 ± 5.34 x 10 -4 µ M/min respectively for dihydrofolic acid (H₂F). The Le. braziliensis rDHFR-TS have Ki values for antimicrobial antifolates in the µM range. Methotrexate (MTX) was a more-potent inhibitor of enzymatic activity (Ki = 22.0 µM) than trimethoprim (Ki = 33 µM) and pyrimethamine (Ki = 68 µM). These Ki values are significantly lower than those obtained for the aporphine alkaloids. The results of the study show the inhibitory effect of antifolate drugs on enzymatic activity, indicating that Le. braziliensis rDHFR-TS could be a model to studying antifolate compounds as potential antiprotozoal drugs.

  16. Bifunctional polydopamine@Fe{sub 3}O{sub 4} core–shell nanoparticles for electrochemical determination of lead(II) and cadmium(II)

    Energy Technology Data Exchange (ETDEWEB)

    Song, Qian; Li, Maoguo, E-mail: limaoguo@mail.ahnu.edu.cn; Huang, Li; Wu, Qikang; Zhou, Yunyou, E-mail: zy161299@mail.ahnu.edu.cn; Wang, Yinling

    2013-07-17

    Highlights: •The bifunctional nanocomposites were synthesized. •A modified magnetic glassy carbon electrode was fabricated. •The electrode was used for the selective detection of Pb{sup 2+} and Cd{sup 2+} ions. •The proposed sensor features a wider linear range and higher sensitivity. -- Abstract: The present paper has focused on the potential application of the bifunctional polydopamine@Fe{sub 3}O{sub 4} core–shell nanoparticles for development of a simple, stable and highly selective electrochemical method for metal ions monitoring in real samples. The electrochemical method is based on electrochemical preconcentration/reduction of metal ions onto a polydopamine@Fe{sub 3}O{sub 4} modified magnetic glassy carbon electrode at −1.1 V (versus SCE) in 0.1 M pH 5.0 acetate solution containing Pb{sup 2+} and Cd{sup 2+} during 160 s, followed by subsequent anodic stripping. The proposed method has been demonstrated highly selective and sensitive detection of Pb{sup 2+} and Cd{sup 2+}, with the calculated detection limits of 1.4 × 10{sup −11} M and 9.2 × 10{sup −11} M. Under the optimized conditions, the square wave anodic stripping voltammetry response of the modified electrode to Pb{sup 2+} (or Cd{sup 2+}) shows a linear concentration range of 5.0–600 nM (or 20–590 nM) with a correlation coefficient of 0.997 (or 0.994). Further, the proposed method has been performed to successfully detect Pb{sup 2+} and Cd{sup 2+} in aqueous effluent.

  17. Bifunctional capsular dosage form: novel fanicular cylindrical gastroretentive system of clarithromycin and immediate release granules of ranitidine HCl for simultaneous delivery.

    Science.gov (United States)

    Rajput, Pallavi; Singh, Deshvir; Pathak, Kamla

    2014-01-30

    The study was aimed to develop a bifunctional single unit capsular system containing gastroretentive funicular cylindrical system (FCS) for controlled local delivery of clarithromycin and immediate release of ranitidine HCl. A 2(3) full factorial design was used to prepare gastroretentive FCS of clarithromycin using polyacrylamide (PAM), HPMC E15LV and Carbopol 934 P. The FCSs were evaluated for % cumulative drug release, floating time and in vitro detachment stress. Among the eight formulations, FCS5 (containing PAM and Carbopol 934 P at high and HPMC E15LV at low levels) showed % cumulative drug release of 97.09±1.14% in 8 h, floating time of 3 h and detachment stress of 8303.64±0.34 dynes/cm(2). Evaluation of optimized FCS by novel dynamic in vitro test proved superior bioadhesivity than cylindrical system under aggressive simulated peristaltic activity. Magnetic resonance imaging elucidated zero order release via constant swelling and erosion of FCS5. In vitro permeability across gastric mucin ensured its potential for effective eradication of deep seated Helicobactor pylori in gastric linings. The optimized FCS was combined with immediate release granules of rantidine HCl to get a bifunctional capsular dosage form. In vitro simultaneous drug release of clarithromycin and rantidine estimated by Vierordt's method exhibited a controlled drug release of 97.72±0.4% in 8 h for clarithromycin through FCS5 and 98.8±1.2% in 60 min from IR granules of ranitidine HCl. The novel system thus established its capability of simultaneous variable delivery of acid suppression agent and macrolide antibiotic that can be advantageous in clinical setting. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. MIL-53(Fe) as a highly efficient bifunctional photocatalyst for the simultaneous reduction of Cr(VI) and oxidation of dyes

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Ruowen; Jing, Fenfen; Shen, Lijuan; Qin, Na; Wu, Ling, E-mail: wuling@fzu.edu.cn

    2015-04-28

    Highlights: • Fe(III)-based MOF was firstly applied to the photocatalytic reduction reaction. • MIL-53(Fe) exhibited an outstanding photocatalytic activity for reduction of Cr(VI). • A first systematic study of the Fe(III)-based MOF as bifunctional photocatalyst. • Dyes and Cr(VI) could be also converted simultaneously over MIL-53(Fe). • MIL-53(Fe) was performed a stable and reusable visible-light-driven photocatalyst. - Abstract: A bifunctional photocatalyst-Fe-benzenedicarboxylate (MIL-53(Fe)) has been synthesized successfully via a facile solvothermal method. The resulting MIL-53(Fe) photocatalyst exhibited an excellent visible light (λ ≥ 420 nm) photocatalytic activity for the reduction of Cr(VI), the reduction rate have reached about 100% after 40 min of visible light irradiation, which has been more efficient than that of N-doped TiO{sub 2} (85%) under identical experimental conditions. Further experimental results have revealed that the photocatalytic activity of MIL-53(Fe) for the reduction of Cr(VI) can be drastically affected by the pH value of the reaction solution, the hole scavenger and atmosphere. Moreover, MIL-53(Fe) has exhibited considerable photocatalytic activity in the mixed systems (Cr(VI)/dyes). After 6 h of visible light illumination, the reduction ratio of Cr(VI) and the degradation ratio of dyes have been exceed 60% and 80%, respectively. More significantly, the synergistic effect can also be found during the process of photocatalytic treatment of Cr(VI) contained wastewater under the same photocatalytic reaction conditions, which makes it a potential candidate for environmental restoration. Finally, a possible reaction mechanism has also been investigated in detail.

  19. Bifunctional coating based on carboxymethyl chitosan with stable conjugated alkaline phosphatase for inhibiting bacterial adhesion and promoting osteogenic differentiation on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Dong; Neoh, Koon Gee, E-mail: chenkg@nus.edu.sg; Kang, En-Tang

    2016-01-01

    Graphical abstract: - Highlights: • Alkaline phosphatase was immobilized on carboxymethyl chitosan coating on Ti. • The coating is bifunctional; resists bacterial adhesion and enhances cell functions. • Osteogenic differentiation of osteoblasts and stem cells is enhanced on the coating. • The coating remains stable and functional after ethanol treatment and autoclaving. - Abstract: In this work, alkaline phosphatase (ALP) was covalently immobilized on carboxymethyl chitosan (CMCS)-coated polydopamine (PDA)-functionalized Ti to achieve a bifunctional surface. Our results showed ∼89% reduction in Staphylococcus epidermidis adhesion on this surface compared to that on pristine Ti. The ALP-modified Ti supported cell proliferation, and significantly enhanced cellular ALP activity and calcium deposition of osteoblasts, human mesenchymal stem cells (hMSCs) and human adipose-derived stem cells (hADSCs). The extent of enhancement in the functions of these cells is dependent on the surface density of immobilized ALP. The substrate prepared using an ALP solution of 50 μg/cm{sup 2} resulted in 44%, 54% and 129% increase in calcium deposited by osteoblasts, hMSCs and hADSCs, respectively, compared to those cultured on pristine Ti. The ALP-modified substrates also promoted the osteogenic differentiation of hMSCs and hADSCs by up-regulating gene expressions of runt-related transcription factor 2 (RUNX2), osterix (OSX), and osteocalcin (OC) in the two types of stem cells. The surface-immobilized ALP was stable after being subjected to 1 h immersion in 70% ethanol and autoclaving at 121 °C for 20 min. However, the enzymatic bioactivity of the surface-immobilized ALP was reduced by about 50% after these substrates were immersed in phosphate buffered saline (PBS) or PBS containing lysozyme for 14 days.

  20. Hydroconversion of methyl laurate on bifunctional Ni2P/AlMCM-41 catalyst prepared via in situ phosphorization using triphenylphosphine

    Science.gov (United States)

    Zhao, Sha; Zhang, Zhena; Zhu, Kongying; Chen, Jixiang

    2017-05-01

    A series of Ni2P/AlMCM-41-x bifunctional catalysts with different Si/Al ratios (x) were synthesized by in situ phosphorization of Ni/AlMCM-41-x with triphenylphosphine (nominal Ni/P ratio of 0.75) at 300 °C on a fixed-bed reactor. For comparison, NiP/AlMCM-41-5-TPR was also prepared by the TPR method from the supported nickel phosphate with the Ni/P ratio of 1.0, during which metallic Ni rather than Ni2P formed. TEM images show that Ni and Ni2P particles uniformly distributed in Ni2P/AlMCM-41-x and NiP/AlMCM-41-5-TPR. The Ni2P/AlMCM-41-x acidity increased with decreasing the Si/Al ratio. In the hydroconversion of methyl laurate, the conversions were close to 100% on all catalysts at 360 °C, 3.0 MPa, methyl laurate WHSV of 2 h-1 and H2/methyl laurate ratio of 25. As to Ni2P/AlMCM-41-x, with decreasing the Si/Al ratio, the total selectivity to C11 and C12 hydrocarbons decreased, while the total selectivity to isoundecane and isododecane (Si-C11+i-C12) firstly increased and then decreased. Ni2P/AlMCM-41-5 gave the largest Si-C11+i-C12 of 43.2%. While NiP/AlMCM-41-5-TPR gave higher Si-C11+i-C12 than Ni2P/AlMCM-41-5, it was more active for the undesired Csbnd C bond cleavage and methanation. We propose that the in-situ phosphorization adopted here is a promising approach to preparing Ni2P-based bifunctional catalysts.

  1. Synthesis and study of bifunctional core–shell nanostructures based on ZnO@Gd{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Babayevska, Nataliya, E-mail: natbab@amu.edu.pl; Nowaczyk, Grzegorz; Jarek, Marcin; Załęski, Karol; Jurga, Stefan

    2016-07-05

    Bifunctional nanostructures based on ZnO nanoparticles (NPs) with controlled Gd{sub 2}O{sub 3} shell thicknesses were obtained by simple low-temperature methods (sol–gel technique and seed deposition method). The morphology, nanostructure, phase and chemical composition as well as luminescent and magnetic properties of the obtained core–shell nanostructures were investigated by transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD) techniques, optical spectroscopy, and SQUID magnetometer. As-obtained ZnO NPs are highly monodispersed and crystalline with mean particles size distribution of about 7 nm. Modification of the ZnO NPs surface by Gd{sub 2}O{sub 3} shell leads to an increase of the ZnO particles size up to 80–160 nm and the formation the Gd{sub 2}O{sub 3} shell with size of 2–4 nm. The dependence of the phase composition, luminescent and magnetic properties on Gd{sub 2}O{sub 3} content are also discussed. - Highlights: • The bifunctional ZnO@Gd{sub 2}O{sub 3} nanostructures were obtained by sol–gel technique. • ZnO@Gd{sub 2}O{sub 3} have intensive luminescence in the visible range under 325 nm excitation. • Gd{sup 3+} content allows to control paramagnetic properties of the ZnO@Gd{sub 2}O{sub 3}. • ZnO@Gd{sub 2}O{sub 3} nanostructures are potential objects for application in medicine.

  2. Protein Foods

    Science.gov (United States)

    ... Text Size: A A A Listen En Español Protein Foods Foods high in protein such as fish, ... for the vegetarian proteins, whether they have carbohydrate. Protein Choices Plant-Based Proteins Plant-based protein foods ...

  3. Essential Role of the Linker Region in the Higher Catalytic Efficiency of a Bifunctional MsrA-MsrB Fusion Protein.

    Science.gov (United States)

    Han, Ah-Reum; Kim, Moon-Jung; Kwak, Geun-Hee; Son, Jonghyeon; Hwang, Kwang Yeon; Kim, Hwa-Young

    2016-09-13

    Many bacteria, particularly pathogens, possess methionine sulfoxide reductase A (MsrA) and B (MsrB) as a fusion form (MsrAB). However, it is not clear why they possess a fusion MsrAB form rather than the separate enzymes that exist in most organisms. In this study, we performed biochemical and kinetic analyses of MsrAB from Treponema denticola (TdMsrAB), single-domain forms (TdMsrA and TdMsrB), and catalytic Cys mutants (TdMsrAB(C11S) and TdMsrAB(C285S)). We found that the catalytic efficiency of both MsrA and MsrB increased after fusion of the domains and that the linker region (iloop) that connects TdMsrA and TdMsrB is required for the higher catalytic efficiency of TdMsrAB. We also determined the crystal structure of TdMsrAB at 2.3 Å, showing that the iloop mainly interacts with TdMsrB via hydrogen bonds. Further kinetic analysis using the iloop mutants revealed that the iloop-TdMsrB interactions are critical to MsrB and MsrA activities. We also report the structure in which an oxidized form of dithiothreitol, an in vitro reductant for MsrA and MsrB, is present in the active site of TdMsrA. Collectively, the results of this study reveal an essential role of the iloop in maintaining the higher catalytic efficiency of the MsrAB fusion enzyme and provide a better understanding of why the MsrAB enzyme exists as a fused form.

  4. The Zygosaccharomyces bailii transcription factor Haa1 is required for acetic acid and copper stress responses suggesting subfunctionalization of the ancestral bifunctional protein Haa1/Cup2.

    Science.gov (United States)

    Palma, Margarida; Dias, Paulo Jorge; Roque, Filipa de Canaveira; Luzia, Laura; Guerreiro, Joana Fernandes; Sá-Correia, Isabel

    2017-01-13

    The food spoilage yeast species Zygosaccharomyces bailii exhibits an extraordinary capacity to tolerate weak acids, in particular acetic acid. In Saccharomyces cerevisiae, the transcription factor Haa1 (ScHaa1) is considered the main player in genomic expression reprogramming in response to acetic acid stress, but the role of its homologue in Z. bailii (ZbHaa1) is unknown. In this study it is demonstrated that ZbHaa1 is a ScHaa1 functional homologue by rescuing the acetic acid susceptibility phenotype of S. cerevisiae haa1Δ. The disruption of ZbHAA1 in Z. bailii IST302 and the expression of an extra ZbHAA1 copy confirmed ZbHAA1 as a determinant of acetic acid tolerance. ZbHaa1 was found to be required for acetic acid stress-induced transcriptional activation of Z. bailii genes homologous to ScHaa1-target genes. An evolutionary analysis of the Haa1 homologues identified in 28 Saccharomycetaceae species genome sequences, including Z bailii, was carried out using phylogenetic and gene neighbourhood approaches. Consistent with previous studies, this analysis revealed a group containing pre-whole genome duplication species Haa1/Cup2 single orthologues, including ZbHaa1, and two groups containing either Haa1 or Cup2 orthologues from post-whole genome duplication species. S. cerevisiae Cup2 (alias Ace1) is a transcription factor involved in response and tolerance to copper stress. Taken together, these observations led us to hypothesize and demonstrate that ZbHaa1 is also involved in copper-induced transcriptional regulation and copper tolerance. The transcription factor ZbHaa1 is required for adaptive response and tolerance to both acetic acid and copper stresses. The subfunctionalization of the single ancestral Haa1/Cup2 orthologue that originated Haa1 and Cup2 paralogues after whole genome duplication is proposed.

  5. Production of bifunctional proteins by Aspergillus awamori: Llama variable heavy chain antibody fragment (VHH) R9 coupled to Arthromyces ramosus peroxidase (ARP)

    NARCIS (Netherlands)

    Joosten, V.; Roelofs, M.S.; Dries, N. van den; Goosen, T.; Verrips, C.T.; Hondel, C.A.M.J.J. van den; Lokman, B.C.

    2005-01-01

    The Arthromyces ramosus peroxidase gene (arp) was genetically fused to either the 5′- or 3′-terminal ends of the gene encoding llama variable heavy chain antibody fragment VHH R9, resulting in the fusion expression cassettes ARP-R9 or R9-ARP. Aspergillus awamori transformants were obtained which

  6. Hydroconversion of methyl laurate on bifunctional Ni{sub 2}P/AlMCM-41 catalyst prepared via in situ phosphorization using triphenylphosphine

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Sha; Zhang, Zhena [Tianjin Key Laboratory of Applied Catalysis Science and Technology, Department of Catalysis Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zhu, Kongying, E-mail: ausky@tju.edu.cn [Analysis and Measurement Center, Tianjin University, Tianjin 300072 (China); Chen, Jixiang, E-mail: jxchen@tju.edu.cn [Tianjin Key Laboratory of Applied Catalysis Science and Technology, Department of Catalysis Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2017-05-15

    Highlights: • Bifunctional Ni{sub 2}P/AlMCM-41 was prepared by in situ phosphorization at 300 °C. • There were similar Ni{sub 2}P particle sizes in Ni{sub 2}P/AlMCM-41 with different Si/Al ratios. • The acid amount of Ni{sub 2}P/AlMCM-41 increased with decreasing the Si/Al ratio. • Ni{sub 2}P/AlMCM-41 with the Si/Al ratio of 5 had the highest activity for isomerization. • Ni{sub 2}P/AlMCM-41 had very low activity for methanation and C−C bond hydrogenolysis. - Abstract: A series of Ni{sub 2}P/AlMCM-41-x bifunctional catalysts with different Si/Al ratios (x) were synthesized by in situ phosphorization of Ni/AlMCM-41-x with triphenylphosphine (nominal Ni/P ratio of 0.75) at 300 °C on a fixed-bed reactor. For comparison, NiP/AlMCM-41-5-TPR was also prepared by the TPR method from the supported nickel phosphate with the Ni/P ratio of 1.0, during which metallic Ni rather than Ni{sub 2}P formed. TEM images show that Ni and Ni{sub 2}P particles uniformly distributed in Ni{sub 2}P/AlMCM-41-x and NiP/AlMCM-41-5-TPR. The Ni{sub 2}P/AlMCM-41-x acidity increased with decreasing the Si/Al ratio. In the hydroconversion of methyl laurate, the conversions were close to 100% on all catalysts at 360 °C, 3.0 MPa, methyl laurate WHSV of 2 h{sup −1} and H{sub 2}/methyl laurate ratio of 25. As to Ni{sub 2}P/AlMCM-41-x, with decreasing the Si/Al ratio, the total selectivity to C11 and C12 hydrocarbons decreased, while the total selectivity to isoundecane and isododecane (S{sub i-C11+i-C12}) firstly increased and then decreased. Ni{sub 2}P/AlMCM-41-5 gave the largest S{sub i-C11+i-C12} of 43.2%. While NiP/AlMCM-41-5-TPR gave higher S{sub i-C11+i-C12} than Ni{sub 2}P/AlMCM-41-5, it was more active for the undesired C−C bond cleavage and methanation. We propose that the in-situ phosphorization adopted here is a promising approach to preparing Ni{sub 2}P-based bifunctional catalysts.

  7. Final Technical Report: Metal—Organic Surface Catalyst for Low-temperature Methane Oxidation: Bi-functional Union of Metal—Organic Complex and Chemically Complementary Surface

    Energy Technology Data Exchange (ETDEWEB)

    Tait, Steven L. [Indiana Univ., Bloomington, IN (United States)

    2016-10-01

    Stabilization and chemical control of transition metal centers is a critical problem in the advancement of heterogeneous catalysts to next-generation catalysts that exhibit high levels of selectivity, while maintaining strong activity and facile catalyst recycling. Supported metal nanoparticle catalysts typically suffer from having a wide range of metal sites with different coordination numbers and varying chemistry. This project is exploring new possibilities in catalysis by combining features of homogeneous catalysts with those of heterogeneous catalysts to develop new, bi-functional systems. The systems are more complex than traditional heterogeneous catalysts in that they utilize sequential active sites to accomplish the desired overall reaction. The interaction of metal—organic catalysts with surface supports and their interactions with reactants to enable the catalysis of critical reactions at lower temperatures are at the focus of this study. Our work targets key fundamental chemistry problems. How do the metal—organic complexes interact with the surface? Can those metal center sites be tuned for selectivity and activity as they are in the homogeneous system by ligand design? What steps are necessary to enable a cooperative chemistry to occur and open opportunities for bi-functional catalyst systems? Study of these systems will develop the concept of bringing together the advantages of heterogeneous catalysis with those of homogeneous catalysis, and take this a step further by pursuing the objective of a bi-functional system. The use of metal-organic complexes in surface catalysts is therefore of interest to create well-defined and highly regular single-site centers. While these are not likely to be stable in the high temperature environments (> 300 °C) typical of industrial heterogeneous catalysts, they could be applied in moderate temperature reactions (100-300 °C), made feasible by lowering reaction temperatures by better catalyst control. They also

  8. Protein-protein interactions

    DEFF Research Database (Denmark)

    Byron, Olwyn; Vestergaard, Bente

    2015-01-01

    Responsive formation of protein:protein interaction (PPI) upon diverse stimuli is a fundament of cellular function. As a consequence, PPIs are complex, adaptive entities, and exist in structurally heterogeneous interplays defined by the energetic states of the free and complexed protomers. The bi...

  9. The bifunctional alcohol and aldehyde dehydrogenase gene, adhE, is necessary for ethanol production in Clostridium thermocellum and Thermoanaerobacterium saccharolyticum.

    Science.gov (United States)

    Lo, Jonathan; Zheng, Tianyong; Hon, Shuen; Olson, Daniel G; Lynd, Lee R

    2015-04-01

    Thermoanaerobacterium saccharolyticum and Clostridium thermocellum are anaerobic thermophilic bacteria being investigated for their ability to produce biofuels from plant biomass. The bifunctional alcohol and aldehyde dehydrogenase gene, adhE, is present in these bacteria and has been known to be important for ethanol formation in other anaerobic alcohol producers. This study explores the inactivation of the adhE gene in C. thermocellum and T. saccharolyticum. Deletion of adhE reduced ethanol production by >95% in both T. saccharolyticum and C. thermocellum, confirming that adhE is necessary for ethanol formation in both organisms. In both adhE deletion strains, fermentation products shifted from ethanol to lactate production and resulted in lower cell density and longer time to reach maximal cell density. In T. saccharolyticum, the adhE deletion strain lost >85% of alcohol dehydrogenase (ADH) activity. Aldehyde dehydrogenase (ALDH) activity did not appear to be affected, although ALDH activity was low in cell extracts. Adding ubiquinone-0 to the ALDH assay increased activity in the T. saccharolyticum parent strain but did not increase activity in the adhE deletion strain, suggesting that ALDH activity was inhibited. In C. thermocellum, the adhE deletion strain lost >90% of ALDH and ADH activity in cell extracts. The C. thermocellum adhE deletion strain contained a point mutation in the lactate dehydrogenase gene, which appears to deregulate its activation by fructose 1,6-bisphosphate, leading to constitutive activation of lactate dehydrogenase. Thermoanaerobacterium saccharolyticum and Clostridium thermocellum are bacteria that have been investigated for their ability to produce biofuels from plant biomass. They have been engineered to produce higher yields of ethanol, yet questions remain about the enzymes responsible for ethanol formation in these bacteria. The genomes of these bacteria encode multiple predicted aldehyde and alcohol dehydrogenases which could be

  10. Evolutionary divergence of chloroplast FAD synthetase proteins

    Directory of Open Access Journals (Sweden)

    Arilla-Luna Sonia

    2010-10-01

    Full Text Available Abstract Background Flavin adenine dinucleotide synthetases (FADSs - a group of bifunctional enzymes that carry out the dual functions of riboflavin phosphorylation to produce flavin mononucleotide (FMN and its subsequent adenylation to generate FAD in most prokaryotes - were studied in plants in terms of sequence, structure and evolutionary history. Results Using a variety of bioinformatics methods we have found that FADS enzymes localized to the chloroplasts, which we term as plant-like FADS proteins, are distributed across a variety of green plant lineages and constitute a divergent protein family clearly of cyanobacterial origin. The C-terminal module of these enzymes does not contain the typical riboflavin kinase active site sequence, while the N-terminal module is broadly conserved. These results agree with a previous work reported by Sandoval et al. in 2008. Furthermore, our observations and preliminary experimental results indicate that the C-terminus of plant-like FADS proteins may contain a catalytic activity, but different to that of their prokaryotic counterparts. In fact, homology models predict that plant-specific conserved residues constitute a distinct active site in the C-terminus. Conclusions A structure-based sequence alignment and an in-depth evolutionary survey of FADS proteins, thought to be crucial in plant metabolism, are reported, which will be essential for the correct annotation of plant genomes and further structural and functional studies. This work is a contribution to our understanding of the evolutionary history of plant-like FADS enzymes, which constitute a new family of FADS proteins whose C-terminal module might be involved in a distinct catalytic activity.

  11. Evolutionary divergence of chloroplast FAD synthetase proteins

    Science.gov (United States)

    2010-01-01

    Background Flavin adenine dinucleotide synthetases (FADSs) - a group of bifunctional enzymes that carry out the dual functions of riboflavin phosphorylation to produce flavin mononucleotide (FMN) and its subsequent adenylation to generate FAD in most prokaryotes - were studied in plants in terms of sequence, structure and evolutionary history. Results Using a variety of bioinformatics methods we have found that FADS enzymes localized to the chloroplasts, which we term as plant-like FADS proteins, are distributed across a variety of green plant lineages and constitute a divergent protein family clearly of cyanobacterial origin. The C-terminal module of these enzymes does not contain the typical riboflavin kinase active site sequence, while the N-terminal module is broadly conserved. These results agree with a previous work reported by Sandoval et al. in 2008. Furthermore, our observations and preliminary experimental results indicate that the C-terminus of plant-like FADS proteins may contain a catalytic activity, but different to that of their prokaryotic counterparts. In fact, homology models predict that plant-specific conserved residues constitute a distinct active site in the C-terminus. Conclusions A structure-based sequence alignment and an in-depth evolutionary survey of FADS proteins, thought to be crucial in plant metabolism, are reported, which will be essential for the correct annotation of plant genomes and further structural and functional studies. This work is a contribution to our understanding of the evolutionary history of plant-like FADS enzymes, which constitute a new family of FADS proteins whose C-terminal module might be involved in a distinct catalytic activity. PMID:20955574

  12. A facile method for the preparation of bifunctional Mn:ZnS/ZnS/Fe3O4 magnetic and fluorescent nanocrystals

    Directory of Open Access Journals (Sweden)

    Houcine Labiadh

    2015-08-01

    Full Text Available Bifunctional magnetic and fluorescent core/shell/shell Mn:ZnS/ZnS/Fe3O4 nanocrystals were synthesized in a basic aqueous solution using 3-mercaptopropionic acid (MPA as a capping ligand. The structural and optical properties of the heterostructures were characterized by X-ray diffraction (XRD, dynamic light scattering (DLS, transmission electron microscopy (TEM, UV–vis spectroscopy and photoluminescence (PL spectroscopy. The PL spectra of Mn:ZnS/ZnS/Fe3O4 quantum dots (QDs showed marked visible emission around 584 nm related to the 4T1 → 6A1 Mn2+ transition. The PL quantum yield (QY and the remnant magnetization can be regulated by varying the thickness of the magnetic shell. The results showed that an increase in the thickness of the Fe3O4 magnetite layer around the Mn:ZnS/ZnS core reduced the PL QY but improved the magnetic properties of the composites. Nevertheless, a good compromise was achieved in order to maintain the dual modality of the nanocrystals, which may be promising candidates for various biological applications.

  13. A systematic study on the utility of CHX-A''-DTPA-NCS and NOTA-NCS as bifunctional chelators for177Lu radiopharmaceuticals.

    Science.gov (United States)

    Pandey, Usha; Gamre, Naresh; Lohar, Sharad Pandurang; Dash, Ashutosh

    2017-09-01

    This paper describes the evaluation of [(R)-2-Amino-3-(4-isothiocyanatophenyl)propyl]-trans-(S,S)-cyclohexane-1,2-diamine-pentaacetic acid (CHX-A''-DTPA-NCS) and 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA-NCS) as bifunctional chelators for 177 Lu. While 177 Lu-CHX-A''-DTPA-NCS could be obtained in high yields at equimolar ratios of lutetium to CHX-A''-DTPA-NCS, >95% yield of 177 Lu-NOTA-NCS could be achieved at 1:2M ratio of lutetium to NOTA-NCS. Trace metals reduced the yields of 177 Lu-NOTA-NCS significantly as compared to 177 Lu-CHX-A''-DTPA-NCS. In vitro stability of 177 Lu-CHX-A''-DTPA-NCS was also superior to 177 Lu-NOTA-NCS. It could be concluded from this study that among the two chelators evaluated, CHX-A''-DTPA-NCS is more appropriate for preparation of 177 Lu radiopharmaceuticals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Cu(II) bifunctional (N,O,O‧) coordination polymer: A case study for complex ab-initio crystal structure determination from PXRD data

    Science.gov (United States)

    Colombo, Valentina; Cimino, Alessandro; Maspero, Angelo; Tollari, Stefano; Palmisano, Giovanni; Sironi, Angelo

    2017-09-01

    The synthesis of a novel Cu(II) bifunctional (N,O,O‧) coordination polymer, the Cu(PzHP) compound, has been carried out by coupling Cu(II) salts and the newely synthesized H2(PzHP) organic linker (H2(PzHP) = 1-[4-(1H) -pyrazolyl]-2-methyl-3-hydroxy-4(1H)-pyridinone). Despite to the numerous attempts done for the growth of suitable single crystals and to the synthetic trials carried out to ameliorate the crystallinity of the Cu(PzHP) coordination polymer, its diffraction pattern was always characterized by a discouraging, less-than-ideal, crystallinity. Notwithstanding the extended disorder, leading to a higher than required space group symmetry, we succeeded in the description of its relevant structural features by following an unconventional route to ab-initio structure solution. In this process consideration on the coordination ability of the ligand and on the space group symmetry have been taken into account to 'manually' achieve the initial structural model, highlighting that, in some cases, it is still possible to ascertain by PXRD the crystal structure of a material that shows challenging, broad, PXRD pattern.

  15. Synthesis of 3D iron and carbon-based composite as a bifunctional sorbent and catalyst for remediation of organic pollutants

    Science.gov (United States)

    Li, Ling; Shen, Yi; Wang, Zhaomei

    2017-07-01

    We prepared a 3D monolith by integrating graphite nanosheet encapsulated iron nanoparticles (Fe@GNS) into graphite felt (GF) supports. The structural properties of the resulting Fe@GNS/GF monolith are characterized by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy and N2 adsorption-desorption isotherms. The Fe@GNS/GF monoliths are utilized as a bifunctional sorbent and catalyst for water remediation. Using Congo red and methyl violet 2B as model pollutants, the sorption and catalytic performance of the Fe@GNS/GF composite are examined. The Fe@GNS/GF monolith possesses maximum sorption capacities of 177 and 142 mg g-1 for the sorption of CR and MV-2B, respectively. It also exhibits rate constants of 0.0563 and 0.0464 min-1 for the catalytic degradation of CR and MV-2B, respectively. As a proof of concept, the Fe@GNS/GF is successfully utilized to decontaminate simulated organic waste water via a combination of sorption and catalytic degradation processes.

  16. Preparation of molecularly imprinted polymeric fibers using a single bifunctional monomer for the solid-phase microextraction of parabens from environmental solid samples.

    Science.gov (United States)

    Díaz-Álvarez, Myriam; Smith, Stephen P; Spivak, David A; Martín-Esteban, Antonio

    2016-02-01

    In this study, molecularly imprinted polymer fibers for solid-phase microextraction have been prepared with a single bifunctional monomer, N,O-bismethacryloyl ethanolamine using the so-called "one monomer molecularly imprinted polymers" method, replacing the conventional combination of functional monomer and cross-linker to form high fidelity binding sites. For comparison, imprinted fibers were prepared following the conventional approach based on ethylene glycol dimethacrylate as cross-linker and methacrylic acid as monomer. The recognition performance of the new fibers was evaluated in the solid-phase microextraction of parabens, and from this study it was concluded that they provided superior performance over conventionally formulated fibers. Ultimately, real-world environmental testing on spiked solid samples was successful by the molecularly imprinted solid-phase microextraction of samples, and the relative recoveries obtained at enrichment levels of 10 ng/g of parabens were within 78-109% for soil and 83-109% for sediments with a relative standard deviation <15% (n = 3). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Cross-link formation between mutant galectins of Caenorhabditis elegans with a substituted cysteine residue and asialofetuin via a photoactivatable bifunctional reagent.

    Science.gov (United States)

    Tamura, Mayumi; Takeuchi, Tomoharu; Nonaka, Takamasa; Kasai, Ken-Ichi; Arata, Yoichiro

    2011-01-01

    LEC-1 is the first tandem repeat-type galectin isolated from an animal system; this galectin has two carbohydrate recognition domains in a single polypeptide chain. Because its two lectin domains have different sugar-binding profiles, these domains are thought to interact with different carbohydrate ligands. In our previous study, we showed that a mutant of LEC-1 in which a cysteine residue was introduced at a unique position in the N-terminal lectin domain (Nh) can be cross-linked with a model glycoprotein ligand, bovine asialofetuin, by using a bifunctional photoactivatable cross-linking reagent, benzophenone-4-maleimide. In the present work, we applied the same procedure to the C-terminal lectin domain (Ch) of LEC-1. Cross-linked products were formed in the cases of two mutants in which a cysteine residue was introduced at Lys¹⁷⁷ and Ser²⁶⁸, respectively. This method is very useful for capturing and assigning endogenous ligand glycoconjugates with relatively low affinities to each carbohydrate recognition domain of the whole tandem repeat-type galectin molecule.

  18. Preparation and characterization of bifunctional dendrimer modified Fe{sub 3}O{sub 4}/CdTe nanoparticles with both luminescent and superparamagnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiuling, E-mail: wxling_self@163.com [Department of Chemical and Biological Engineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Gu, Yinjun; Dong, Shuling [Department of Chemical and Biological Engineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Zhao, Qin [School of Chemistry and Chemical Engineering, Nantong University, Nantong, Jiangsu 226019 (China); Liu, Yongjian [Department of Chemical and Biological Engineering, Suzhou University of Science and Technology, Suzhou 215009 (China)

    2015-10-15

    Highlights: • The fluorescent superparamagnetic dendrimeric Fe{sub 3}O{sub 4}/CdTe nanoparticles are synthesized in this paper. • The synthesized nanocomposites maintain excellent magnetic properties. • The synthesized nanocomposites maintain highly luminescent markers with narrow emission bands. - Abstract: Magnetic nanoparticles Fe{sub 3}O{sub 4} were prepared by hydrothermal coprecipitation of ferric and ferrous ions using NaOH. The surface modification of Fe{sub 3}O{sub 4} nanoparticle by dendrimers has rendered the nanoparticle surface with enriched amine groups which facilitated the adsorption and conjugation of thioglycolic acid (TGA) modified CdTe quantum dots to form a stable hybrid nanostructure. Three generations (first generation: G0F, second generation: G1F, third generation: G3F) of bifunctional dendrimeric Fe{sub 3}O{sub 4}/CdTe nanoparticles were successfully prepared using this technique and characterized by microscopy. The optical and magnetic properties of the dendrimeric Fe{sub 3}O{sub 4}/CdTe nanoparticle were also investigated. The microscopic study reveals 3 different sizes for 3 generations, 16 nm (G0F), 31 nm (G1F) and 47 nm (G3F). Among three generations of nanoparticles, the G1F has the best optical property with a luminescent quantum yield of 25.6% and the G0F has the best magnetic property with a saturation magnetization of 19.3 emμ/g.

  19. Ethanolysis conversion of spent frying oils over aluminium, calcium-phosphate based bi-functional formulated catalysts. Catalytic activity assessment study

    Energy Technology Data Exchange (ETDEWEB)

    Al-Zaini, Essam O.; Chesterfield, Dean; Adesina, Adesoji A. [The Univ. of New South Wales, Sydney (Australia). Reactor Engineering and Technology Group; Olsen, John [The Univ. of New South Wales, Sydney (Australia). School of Mechanical and Manufacturing Engineering

    2013-06-01

    The current study compares the catalytic performance of two bi-functional solid catalysts for the transesterification of waste cooking vegetable oil in presence of bio-ethanol acyl-acceptor. The two catalysts were aluminum oxide and seashell-derived calcium oxide supported K{sub 3}PO{sub 4}. The catalytic activity of the produced catalyst samples were assessed and evaluated in terms of their textural and surface chemical properties. Evaluative runs showed that increased amounts of K{sub 3}PO{sub 4} have differently controlled the textural and surface chemical property of the finally synthesised catalyst samples. The behaviour revealed a strong correlation between the percentage yield of ethyl esters EEY% and acid-base site density and strength between the two types of catalysts. Possible leaching test of the catalysts was also used as a measure of performance and as a result, the optimum catalyst, on the basis of both ester yield and resistance to leaching was identified as the sample containing between 10 and 15wt% of K{sub 3}PO{sub 4} on AlO{sub 3} and CaO respectively. (orig.)

  20. MIL-53(Fe) as a highly efficient bifunctional photocatalyst for the simultaneous reduction of Cr(VI) and oxidation of dyes.

    Science.gov (United States)

    Liang, Ruowen; Jing, Fenfen; Shen, Lijuan; Qin, Na; Wu, Ling

    2015-04-28

    A bifunctional photocatalyst-Fe-benzenedicarboxylate (MIL-53(Fe)) has been synthesized successfully via a facile solvothermal method. The resulting MIL-53(Fe) photocatalyst exhibited an excellent visible light (λ≥ 420nm) photocatalytic activity for the reduction of Cr(VI), the reduction rate have reached about 100% after 40min of visible light irradiation, which has been more efficient than that of N-doped TiO2 (85%) under identical experimental conditions. Further experimental results have revealed that the photocatalytic activity of MIL-53(Fe) for the reduction of Cr(VI) can be drastically affected by the pH value of the reaction solution, the hole scavenger and atmosphere. Moreover, MIL-53(Fe) has exhibited considerable photocatalytic activity in the mixed systems (Cr(VI)/dyes). After 6h of visible light illumination, the reduction ratio of Cr(VI) and the degradation ratio of dyes have been exceed 60% and 80%, respectively. More significantly, the synergistic effect can also be found during the process of photocatalytic treatment of Cr(VI) contained wastewater under the same photocatalytic reaction conditions, which makes it a potential candidate for environmental restoration. Finally, a possible reaction mechanism has also been investigated in detail. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. A facile method for the preparation of bifunctional Mn:ZnS/ZnS/Fe3O4 magnetic and fluorescent nanocrystals.

    Science.gov (United States)

    Labiadh, Houcine; Ben Chaabane, Tahar; Sibille, Romain; Balan, Lavinia; Schneider, Raphaël

    2015-01-01

    Bifunctional magnetic and fluorescent core/shell/shell Mn:ZnS/ZnS/Fe3O4 nanocrystals were synthesized in a basic aqueous solution using 3-mercaptopropionic acid (MPA) as a capping ligand. The structural and optical properties of the heterostructures were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), UV-vis spectroscopy and photoluminescence (PL) spectroscopy. The PL spectra of Mn:ZnS/ZnS/Fe3O4 quantum dots (QDs) showed marked visible emission around 584 nm related to the (4)T1 → (6)A1 Mn(2+) transition. The PL quantum yield (QY) and the remnant magnetization can be regulated by varying the thickness of the magnetic shell. The results showed that an increase in the thickness of the Fe3O4 magnetite layer around the Mn:ZnS/ZnS core reduced the PL QY but improved the magnetic properties of the composites. Nevertheless, a good compromise was achieved in order to maintain the dual modality of the nanocrystals, which may be promising candidates for various biological applications.

  2. Dissolution of arterial platelet thrombi in vivo with a bifunctional platelet GPIIIa49-66 ligand which specifically targets the platelet thrombus.

    Science.gov (United States)

    Zhang, Wei; Li, Yong-Sheng; Nardi, Michael A; Dang, Suying; Yang, Jing; Ji, Yong; Li, Zongdong; Karpatkin, Simon; Wisniewski, Thomas

    2010-09-30

    Patients with HIV-1 immune-related thrombocytopenia have a unique antibody (Ab) against integrin GPIIIa49-66 capable of inducing oxidative platelet fragmentation via Ab activation of platelet nicotinamide adenine dinucleotide phosphate oxidase and 12-lipoxygenase releasing reactive oxygen species. Using a phage display single-chain antibody (scFv) library, we developed a novel human monoclonal scFv Ab against GPIIIa49-66 (named A11) capable of inducing fragmentation of activated platelets. In this study, we investigated the in vivo use of A11. We show that A11 does not induce significant thrombocytopenia or inhibit platelet function. A11 can prevent the cessation of carotid artery flow produced by induced artery injury and dissolve the induced thrombus 2 hours after cessation of blood flow. In addition, A11 can prevent, as well as ameliorate, murine middle cerebral artery stroke, without thrombocytopenia or brain hemorrhage. To further optimize the antithrombotic activity of A11, we produced a bifunctional A11-plasminogen first kringle agent (SLK), which homes to newly deposited fibrin strands within and surrounding the platelet thrombus, reducing effects on nonactivated circulating platelets. Indeed, SLK is able to completely reopen occluded carotid vessels 4 hours after cessation of blood flow, whereas A11 had no effect at 4 hours. Thus, a new antithrombotic agent was developed for platelet thrombus clearance.

  3. The urchin-like sphere arrays Co3O4 as a bifunctional catalyst for hydrogen evolution reaction and oxygen evolution reaction

    Science.gov (United States)

    Li, Ruchun; Zhou, Dan; Luo, Jiaxian; Xu, Weiming; Li, Jingwei; Li, Shuoshuo; Cheng, Pengpeng; Yuan, Dingsheng

    2017-02-01

    Electrochemical water splitting has attracted great interest because of the growing demand for sustainable energy and increasing concerns for the environment. We present a facile strategy to design the three-dimensional (3D) urchin-like sphere arrays Co3O4 as an effective bifunctional catalyst for electrochemical water splitting. The 3D urchin-like Co3O4 was directly grown on Ni foam by a hydrothermal reaction and annealing treatment at a low temperature. This process offers several advantages including facile synthesis, binder-free, and low cost. The 3D urchin-like Co3O4 as a catalyst for hydrogen evolution reaction exhibits a low onset potential (-130 mV vs. RHE) and good cycling stability in an alkaline electrolyte. When urchin-like Co3O4 is used as a catalyst for oxygen evolution reaction, the onset potential is at 1.46 V (vs. RHE) with a low overpotential of only 230 mV. The good catalytic activity can be attributed to the unique urchin-like nanostructure, abundant mesopores, and low charge-transfer resistance (compared with Co3O4 NPs). In addition, H2 and O2 generation was performed using Co3O4 as both cathode and anode catalysts with a potential of 1.64 V to reach a current density of 10 mA cm-2.

  4. The Quest for Converting Biorenewable Bifunctional α-Methylene-γ-butyrolactone into Degradable and Recyclable Polyester: Controlling Vinyl-Addition/Ring-Opening/Cross-Linking Pathways

    KAUST Repository

    Tang, Xiaoyan

    2016-10-04

    α-Methylene-γ-butyrolactone (MBL), a naturally occurring and biomass-sourced bifunctional monomer, contains both a highly reactive exocyclic C═C bond and a highly stable five-membered γ-butyrolactone ring. Thus, all previous work led to exclusive vinyl-addition polymerization (VAP) product P(MBL)VAP. Now, this work reverses this conventional chemoselectivity to enable the first ring-opening polymerization (ROP) of MBL, thereby producing exclusively unsaturated polyester P(MBL)ROP with Mn up to 21.0 kg/mol. This elusive goal was achieved through uncovering the thermodynamic, catalytic, and processing conditions. A third reaction pathway has also been discovered, which is a crossover propagation between VAP and ROP processes, thus affording cross-linked polymer P(MBL)CLP. The formation of the three types of polymers, P(MBL)VAP, P(MBL)CLP, and P(MBL)ROP, can be readily controlled by adjusting the catalyst (La)/initiator (ROH) ratio, which is determined by the unique chemoselectivity of the La–X (X = OR, NR2, R) group. The resulting P(MBL)ROP is degradable and can be readily postfunctionalized into cross-linked or thiolated materials but, more remarkably, can also be fully recycled back to its monomer thermochemically. Computational studies provided the theoretical basis for, and a mechanistic understanding of, the three different polymerization processes and the origin of the chemoselectivity.

  5. Highly Selective Bifunctional Luminescent Sensor toward Nitrobenzene and Cu2+ Ion Based on Microporous Metal-Organic Frameworks: Synthesis, Structures, and Properties.

    Science.gov (United States)

    Yang, Lirong; Lian, Chen; Li, Xuefei; Han, Yuyang; Yang, Lele; Cai, Ting; Shao, Caiyun

    2017-05-24

    Two metal-organic frameworks (MOFs), namely, [Ni(DTP)(H2O)]n (I) and [Cd2(DTP)2(bibp)1.5]n (II) (H2DPT = 4'-(4-(3,5-dicarboxylphenoxy) phenyl)-4,2':6',4″-terpyridine; bibp = 1,3-di(1H-imidazol-1-yl)propane), that present structural diversity were solvothermally prepared. Single-crystal X-ray diffraction analysis indicates that they consist of {NiN2O4} building units (for I) and {CdO4N2} and {CdO3N3} building units (for II), which are further linked by multicarboxylate H2DPT to construct microporous three-dimensional frameworks. The remarkable character of these frameworks is that coordination polymer II demonstrates highly selective and sensitive bifunctional luminescent sensor toward nitrobenzene and Cu2+ ion. The fluorescence quenching mechanism of II caused by nitrobenzene is ascribed to electron transfer from electron-rich (II) to electron-deficient nitrobenzene. The result was also evidenced by the density functional theory. Furthermore, anti-ferromagnetic as well as electrochemical characters of Ni-MOF (I) were also investigated in this paper.

  6. Bifunctional coating based on carboxymethyl chitosan with stable conjugated alkaline phosphatase for inhibiting bacterial adhesion and promoting osteogenic differentiation on titanium

    Science.gov (United States)

    Zheng, Dong; Neoh, Koon Gee; Kang, En-Tang

    2016-01-01

    In this work, alkaline phosphatase (ALP) was covalently immobilized on carboxymethyl chitosan (CMCS)-coated polydopamine (PDA)-functionalized Ti to achieve a bifunctional surface. Our results showed ∼89% reduction in Staphylococcus epidermidis adhesion on this surface compared to that on pristine Ti. The ALP-modified Ti supported cell proliferation, and significantly enhanced cellular ALP activity and calcium deposition of osteoblasts, human mesenchymal stem cells (hMSCs) and human adipose-derived stem cells (hADSCs). The extent of enhancement in the functions of these cells is dependent on the surface density of immobilized ALP. The substrate prepared using an ALP solution of 50 μg/cm2 resulted in 44%, 54% and 129% increase in calcium deposited by osteoblasts, hMSCs and hADSCs, respectively, compared to those cultured on pristine Ti. The ALP-modified substrates also promoted the osteogenic differentiation of hMSCs and hADSCs by up-regulating gene expressions of runt-related transcription factor 2 (RUNX2), osterix (OSX), and osteocalcin (OC) in the two types of stem cells. The surface-immobilized ALP was stable after being subjected to 1 h immersion in 70% ethanol and autoclaving at 121 °C for 20 min. However, the enzymatic bioactivity of the surface-immobilized ALP was reduced by about 50% after these substrates were immersed in phosphate buffered saline (PBS) or PBS containing lysozyme for 14 days.

  7. Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol/Chitosan Blend Films: Fabrication, Characterization and Properties

    Directory of Open Access Journals (Sweden)

    Susan Azizi

    2014-06-01

    Full Text Available In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol (PVA and chitosan (Cs blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses.

  8. Survival and bioactivities of selected probiotic lactobacilli in yogurt fermentation and cold storage: New insights for developing a bi-functional dairy food.

    Science.gov (United States)

    Rutella, Giuseppina Sefora; Tagliazucchi, Davide; Solieri, Lisa

    2016-12-01

    In previous work, we demonstrated that two probiotic strains, namely Lactobacillus casei PRA205 and Lactobacillus rhamnosus PRA331, produce fermented milks with potent angiotensin-converting enzyme (ACE)-inhibitory and antioxidant activities. Here, we tested these strains for the survivability and the release of antihypertensive and antioxidant peptides in yogurt fermentation and cold storage. For these purposes three yogurt batches were compared: one prepared using yogurt starters alone (Lactobacillus delbrueckii subspecies bulgaricus 1932 and Streptococcus thermophilus 99), and the remaining two containing either PRA205 or PRA331 in addition to yogurt starters. Despite the lower viable counts at the fermentation end compared to PRA331, PRA205 overcame PRA331 in survivability during refrigerated storage for 28 days, leading to viable counts (>10(8) CFU/g) higher than the minimum therapeutic threshold (10(6) CFU/g). Analyses of in vitro ACE-inhibitory and antioxidant activities of peptide fractions revealed that yogurt supplemented with PRA205 displays higher amounts of antihypertensive and antioxidant peptides than that produced with PRA331 at the end of fermentation and over storage. Two ACE-inhibitory peptides, Valine-Proline-Proline (VPP) and Isoleucine-Proline-Proline (IPP), were identified and quantified. This study demonstrated that L. casei PRA205 could be used as adjunct culture for producing bi-functional yogurt enriched in bioactive peptides and in viable cells, which bring health benefits to the host as probiotics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Overexpression, purification and crystallization of the two C-terminal domains of the bifunctional cellulase ctCel9D-Cel44A from Clostridium thermocellum

    Energy Technology Data Exchange (ETDEWEB)

    Najmudin, Shabir [REQUIMTE, Departamento de Química, FCT-UNL, 2829-516 Caparica (Portugal); Guerreiro, Catarina I. P. D.; Ferreira, Luís M. A. [CIISA - Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa (Portugal); Romão, Maria J. C. [REQUIMTE, Departamento de Química, FCT-UNL, 2829-516 Caparica (Portugal); Fontes, Carlos M. G. A.; Prates, José A. M., E-mail: japrates@fmv.utl.pt [CIISA - Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa (Portugal); REQUIMTE, Departamento de Química, FCT-UNL, 2829-516 Caparica (Portugal)

    2005-12-01

    The two C-terminal domains of the cellulase ctCel9D-Cel44A from C. thermocellum cellulosome have been crystallized in tetragonal space group P4{sub 3}2{sub 1}2 and X-ray diffraction data have been collected to 2.1 and 2.8 Å from native and seleno-l-methionine-derivative crystals, respectively. Clostridium thermocellum produces a highly organized multi-enzyme complex of cellulases and hemicellulases for the hydrolysis of plant cell-wall polysaccharides, which is termed the cellulosome. The bifunctional multi-modular cellulase ctCel9D-Cel44A is one of the largest components of the C. thermocellum cellulosome. The enzyme contains two internal catalytic domains belonging to glycoside hydrolase families 9 and 44. The C-terminus of this cellulase, comprising a polycystic kidney-disease module (PKD) and a carbohydrate-binding module (CBM44), has been crystallized. The crystals belong to the tetragonal space group P4{sub 3}2{sub 1}2, containing a single molecule in the asymmetric unit. Native and seleno-l-methionine-derivative crystals diffracted to 2.1 and 2.8 Å, respectively.

  10. Novel trends in electrocatalysis: Extended Brewer hypo-hyper-d-interionic bonding theory and selective interactive grafting of composite bifunctional electrocatalysts for simultaneous anodic hydrogen

    Directory of Open Access Journals (Sweden)

    Neophytides S.G.

    2003-01-01

    Full Text Available Novel Trends in Electrocatalysis: Extended Brewer Hypo-Hyper-d-lnterionic Bonding Theory and Selective Interactive Grafting of Composite Bifunctional Electrocatalysts for Simultaneous Anodic Hydrogen and CO OxidationThe Extended Brewer Interactive Interionic Bonding Theory (EBIIBT has been developed to show the equivalence of interatomic and interionic bonding features, and for their mutual combinations, as well as its effect upon electrocatalytic properties for the hydrogen electrode reactions (HELR. The equivalence of interionic hypo-hyper-d-interelectronic interaction in both metallic and any other ionic state and its effect upon electrocatalytic properties for hydrogen electrode reactions (HELR has been proved and inferred. TG (Thermal Gravimetry analysis of TPR (Temperature Programmed Reduction of mixed hypc-hyper-d-electronic oxides of transition elements was broadly employed to prove the EBIIBT effect as reflected in dramatically decreased individual temperatures of their mutual reduction into intermetallic phases. The same interionic Brewer (and/or intermetallic bonding effect has been confirmed both by UPD of hyper-d-upon hypo-d-electronic substrates and vice versa, and by the shift of bonding peaks in XPS analysis.

  11. Fe3O4@polyaniline yolk-shell micro/nanospheres as bifunctional materials for lithium storage and electromagnetic wave absorption

    Science.gov (United States)

    Wang, Xiaoliang; Zhang, Minwei; Zhao, Jianming; Huang, Guoyong; Sun, Hongyu

    2018-01-01

    Unique Fe3O4/polyaniline (PANI) composite with yolk-shell micro/nanostructure (FPys) has been successfully synthesized by a facile silica-assisted in-situ polymerization and subsequent etching strategy. The structural and compositional studies of the FPys composites are performed by employing X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The yolk-shell morphology of the products is confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. When evaluated as anode material for lithium-ion batteries, the as-prepared FPys electrodes deliver superior capacity, better cycling stability and rate capability than those of bare Fe3O4 micro/nanospheres and Fe3O4/PANI core-shell (FPcs) electrodes. Moreover, FPys also exhibits excellent electromagnetic wave absorption performance when comparing to the synthesized Fe3O4-based electromagnetic wave absorbers, in which strong reflection loss and extensive response bandwidth can be achieved simultaneously. The excellent bifunctional properties of FPys material are associated with the specially designed hierarchical micro/nanostructures. The current strategy that application directed structural design can be applied to the synthesis of other multifunctional materials.

  12. 2-Fold Interpenetrating Bifunctional Cd-Metal-Organic Frameworks: Highly Selective Adsorption for CO2and Sensitive Luminescent Sensing of Nitro Aromatic 2,4,6-Trinitrophenol.

    Science.gov (United States)

    Hong, Xu-Jia; Wei, Qin; Cai, Yue-Peng; Zheng, Sheng-Run; Yu, Ying; Fan, Yan-Zhong; Xu, Xian-Yan; Si, Li-Ping

    2017-02-08

    A robust primitive diamond-type topology 3-D metal-organic framework (MOF) of {[Cd 4 (hbhdpy) 2 (bdc) 3 (DMA) 2 ]·(H 2 O) 4 } n (1, DMA = N,N-dimethylacetamide) was constructed from the planar secondary building units of the dinuclear cadmium clusters, Cd 2 (μ 2 -O) 2 , and two linear organic linkers of the new multidentate Schiff base of 4-(2-hydroxy-3-methoxy-benzyli-denehydrazino-carbonyl)-N-pyridin-4-yl-benzamide (Hhbhdpy) through the solvothermal reaction. 1 presents a 2-fold interpenetrating network along with confined narrow channels and rich acylamide groups as well as potential metal open sites for excellent selective CO 2 uptake over CH 4 /N 2 and high luminescent response for 2,4,6-trinitrophenol (TNP) in DMA solution under ambient conditions. With 2-amino-1,4-dicarboxy-benzene (H 2 bdc-NH 2 ) replacing H 2 bdc, an amine-functionalized MOF of {[Cd 4 (hbhdpy) 2 (bdc-NH 2 ) 3 (DMA) 2 ]·(H 2 O) 4 } n (1-NH 2 ) as an isomorphism of 1, was synthesized under the same reaction conditions. Compared with 1, the corresponding bifunctional features of 1-NH 2 is more obvious. To the best of our knowledge, it is the first reported interpenetrating Cd-MOFs with highly sensitive luminescence response for TNP molecules combined with excellent selectivity for CO 2 /N 2 and CO 2 /CH 4 .

  13. Rhenium and Technetium-oxo Complexes with Thioamide Derivatives of Pyridylhydrazine Bifunctional Chelators Conjugated to the Tumour Targeting Peptides Octreotate and Cyclic-RGDfK.

    Science.gov (United States)

    North, Andrea J; Karas, John A; Ma, Michelle T; Blower, Philip J; Ackermann, Uwe; White, Jonathan M; Donnelly, Paul S

    2017-08-21

    This research aimed to develop new tumor targeted theranostic agents taking advantage of the similarities in coordination chemistry between technetium and rhenium. A γ-emitting radioactive isotope of technetium is commonly used in diagnostic imaging, and there are two β(-) emitting radioactive isotopes of rhenium that have the potential to be of use in radiotherapy. Variants of the 6-hydrazinonicotinamide (HYNIC) bifunctional ligands have been prepared by appending thioamide functional groups to 6-hydrazinonicotinamide to form pyridylthiosemicarbazide ligands (SHYNIC). The new bidentate ligands were conjugated to the tumor targeting peptides Tyr(3)-octreotate and cyclic-RGD. The new ligands and conjugates were used to prepare well-defined {M═O}(3+) complexes (where M = (99m)Tc or (nat)Re or (188)Re) that feature two targeting peptides attached to the single metal ion. These new SHYNIC ligands are capable of forming well-defined rhenium and technetium complexes and offer the possibility of using the (99m)Tc imaging and (188/186)Re therapeutic matched pairs.

  14. Adsorption of humic acid by bi-functional resin JN-10 and the effect of alkali-earth metal ions on the adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jinnan; Zhou Yang [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Research Center of Organic Toxic Substance Control and Resource Reuse of Jiangsu Province, Nanjing 210038 (China); Li Aimin, E-mail: liaimin99@vip.sina.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Research Center of Organic Toxic Substance Control and Resource Reuse of Jiangsu Province, Nanjing 210038 (China); Xu Li [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Research Center of Organic Toxic Substance Control and Resource Reuse of Jiangsu Province, Nanjing 210038 (China)

    2010-04-15

    This study investigated the adsorption of humic acid (HA) by bi-functional resin JN-10, which removed the HA more effectively than the commercial resins D-301, D-201, XAD-7, and globe active carbon F-400. The difference between the FT-IR spectroscopy and {sup 13}C NMR analysis of JN-10 before and after it adsorbing the HA revealed that both hydrophobic interaction and electric attraction were the adsorption force for the HA. The related thermodynamic parameters exhibited that the adsorption of the HA by JN-10 was an endothermic process. The occurring of adsorption was due to the increase of entropy, and the electric attraction was also a main adsorption force. In order to investigate the influence of the molecule weight (MW) of the HA on its removal by JN-10, the HA with the MWs ranging from 2000 to 100,000 Da was divided into six fractions by ultra-filtration. The HA with a medium MW (6000-10,000 Da) was preferentially removed by JN-10 due to the synergistic effect of hydrophilicity, molecular size, and aromaticity of the HA. The adsorption capacity of JN-10 for the HA increased in the presence of low concentration of alkali-earth metal ions Ca{sup 2+} and Mg{sup 2+}, which neutralized the negative charges of the HA, but it decreased as the concentration of these ions increased because the hydrates formed by the alkali-earth metal ions occupied the adsorption sites of the resin.

  15. Bifunctional silver(I) complex-catalyzed CO2 conversion at ambient conditions: synthesis of α-methylene cyclic carbonates and derivatives.

    Science.gov (United States)

    Song, Qing-Wen; Chen, Wei-Qiang; Ma, Ran; Yu, Ao; Li, Qiu-Yue; Chang, Yao; He, Liang-Nian

    2015-03-01

    The chemical conversion of CO2 at atmospheric pressure and room temperature remains a great challenge. The triphenylphosphine complex of silver(I) carbonate was proved to be a robust bifunctional catalyst for the carboxylative cyclization of propargylic alcohols and CO2 at ambient conditions leading to the formation of α-methylene cyclic carbonates in excellent yields. The unprecedented performance of [(PPh3)2Ag]2CO3 is presumably attributed to the simultaneous activation of CO2 and propargylic alcohol. Moreover, the highly compatible basicity of the catalytic species allows propargylic alcohol to react with CO2 leading to key silver alkylcarbonate intermediates: the bulkier [(Ph3P)2Ag(I)](+) effectively activates the carbon-carbon triple bond and enhances O-nucleophilicity of the alkylcarbonic anion, thereby greatly promoting the intramolecular nucleophilic cyclization. Notably, this catalytic protocol also worked well for the reaction of propargylic alcohols, secondary amines, and CO2 (at atmospheric pressure) to afford β-oxopropylcarbamates. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. MnCo2O4 nanowires anchored on reduced graphene oxide sheets as effective bifunctional catalysts for Li-O2 battery cathodes.

    Science.gov (United States)

    Kim, Jong Guk; Kim, Youngmin; Noh, Yuseong; Kim, Won Bae

    2015-05-22

    A hybrid composite system of MnCo2 O4 nanowires (MCO NWs) anchored on reduced graphene oxide (RGO) nanosheets was prepared as the bifunctional catalyst of a Li-O2 battery cathode. The catalysts can be obtained from the hybridization of one-dimensional MCO NWs and two-dimensional RGO nanosheets. As O2 -cathode catalysts for Li-O2 cells, the MCO@RGO composites showed a high initial discharge capacity (ca. 11092.1 mAh gcarbon (-1) ) with a high rate performance. The Li-O2 cells could run for more than 35 cycles with high reversibility under a limited specific capacity of 1000 mAh gcarbon (-1) with a low potential polarization of 1.36 V, as compared with those of pure Ketjenblack and MCO NWs. The high cycling stability, low potential polarization, and rate capability suggest that the MCO@RGO composites prepared here are promising catalyst candidates for highly reversible Li-O2 battery cathodes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Three-Dimensional Framework of Graphene Nanomeshes Shell/Co3O4Synthesized as Superior Bifunctional Electrocatalyst for Zinc-Air Batteries.

    Science.gov (United States)

    Wang, Congwei; Zhao, Zheng; Li, Xiaofeng; Yan, Rui; Wang, Jie; Li, Anni; Duan, Xiaoyong; Wang, Junying; Liu, Yong; Wang, Junzhong

    2017-11-29

    The synthesis of durable and low-cost electrocatalyst is crucial but challenging. Here, we developed a one-pot pyrolysis approach toward the preparation of heteroatom-doped hierarchical porous three-dimensional (3D) graphene frameworks decorated with multilayer graphene shell-coated cobalt oxide nanocrystal. Large literal sheet size of graphene nanomeshes may stimulate rapid thermolysis with cobalt-oleate complex to form Co 3 O 4 nanocrystals and in situ growth of multilayer graphene coating co-doped by boron and nitrogen with controlling heating rate up to 600 °C. This new material worked as superior bifunctional electrocatalyst on oxygen reduction reaction and oxygen evolution reaction to commercial Pt/C with better onset potential/half-wave potentials, larger current density, better stability, and stronger methanol tolerance. The heteroatom co-doping into porous/curved graphene confined nanocrystals in 3D porous walls provided adequate accessibility of created catalytic active sites and ideal mass transport route for the excellent catalytic activity on redox reaction of oxygen. The synthesized material-based Zn-air battery further confirmed its superior electrolytic activity with high specific capacity and smaller overpotential. This one-pot pyrolysis method shows a great potential of scalable synthesis of high-performance practical electrocatalyst for metal-air batteries and fuel cells at a low cost.

  18. Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Thamake, S I; Raut, S L [Department of Biomedical Sciences, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107 (United States); Ranjan, A P; Vishwanatha, J K [Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States); Gryczynski, Z, E-mail: jamboor.vishwanatha@unthsc.edu [Center for Commercialization of Fluorescence Technology, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States)

    2011-01-21

    This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

  19. Magnetic amine-functionalized graphene oxide as a novel and recyclable bifunctional nanocatalyst for solvent-free synthesis of pyrano[3,2-c]pyridine derivatives

    Directory of Open Access Journals (Sweden)

    Shahnaz Rostamizadeh

    2017-01-01

    Full Text Available The new magnetic amine-functionalized graphene oxide (Fe3O4-GO-NH2 nanocatalyst was prepared through the reaction of 3-aminopropyltriethoxysilane (APTES with magnetic graphene oxide (Fe3O4-GO. It was characterized by XRD, TEM, SEM, FT-IR and EDX techniques. The intrinsic carboxylic acids on the edges of Fe3O4-GO along with the amine groups post grafted to the surface of Fe3O4-GO led to preparation of an acid-base bifunctional magnetically recyclable nanocatalyst. It proved to be efficient nanocatalyst for solvent-free synthesis of pyrano[3,2-c]pyridine derivatives under mild reaction conditions with good to excellent yields. This heterogeneous catalyst also exhibited higher activities than acid or base functionalized mesoporous silica, magnetic GO or basic Al2O3 an even higher than some basic homogeneous catalysts such as triethylamine and piperazine. More importantly, due to the loaded iron oxide nanoparticles, this catalyst could be easily recovered from the reaction mixture using an external magnet and reused without significant decrease in activity even after 7 runs.

  20. Investigation on the influence of metal ion impurities on the complexation behavior of generator produced {sup 90}Y with different bifunctional chelators

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Usha; Gamre, Naresh; Chakravarty, Rubel; Pillai, Maroor Raghavan Ambikalmajan; Dash, Ashutosh [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Radiopharmaceuticals Div.

    2014-07-01

    While the {sup 90}Sr/{sup 90}Y generator is the exclusive source of obtaining 'no carrier added' {sup 90}Y for targeted therapy, the presence of trace metals in the radiolabeling solutions poses a serious challenge owing to their ability to diminish the {sup 90}Y complexation yields with bifunctional chelators (BFCs). p-SCN-Bn-PCTA is a novel ligand having faster complexation kinetics with a number of radiometals. In this work, a systematic investigation was performed to evaluate the chelating ability of p-SCN-Bn-PCTA for {sup 90}Y and the influence of trace metal ions on it's complexation with {sup 90}Y in comparison to p-SCN-Bn-DTPA and p-SCN-Bn-DOTA using {sup 90}YCl{sub 3} obtained from an electrochemical generator. Results from our study indicate that while p-SCN-Bn-PCTA gave very good radiolabeling yields with {sup 90}Y when the reaction was carried out by heating for few minutes, it was most sensitive to the presence of trace metals, especially Fe(III). An independent and useful observation is that p-SCN-Bn-PCTA could be considered as the ligand of choice for assessing the chemical purity of generator derived {sup 90}Y.

  1. Highly active, bi-functional and metal-free B4C-nanoparticle-modified graphite felt electrodes for vanadium redox flow batteries

    Science.gov (United States)

    Jiang, H. R.; Shyy, W.; Wu, M. C.; Wei, L.; Zhao, T. S.

    2017-10-01

    The potential of B4C as a metal-free catalyst for vanadium redox reactions is investigated by first-principles calculations. Results show that the central carbon atom of B4C can act as a highly active reaction site for redox reactions, due primarily to the abundant unpaired electrons around it. The catalytic effect is then verified experimentally by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests, both of which demonstrate that B4C nanoparticles can enhance the kinetics for both V2+/V3+ and VO2+/VO2+ redox reactions, indicating a bi-functional effect. The B4C-nanoparticle-modified graphite felt electrodes are finally prepared and tested in vanadium redox flow batteries (VRFBs). It is shown that the batteries with the prepared electrodes exhibit energy efficiencies of 88.9% and 80.0% at the current densities of 80 and 160 mA cm-2, which are 16.6% and 18.8% higher than those with the original graphite felt electrodes. With a further increase in current densities to 240 and 320 mA cm-2, the batteries can still maintain energy efficiencies of 72.0% and 63.8%, respectively. All these results show that the B4C-nanoparticle-modified graphite felt electrode outperforms existing metal-free catalyst modified electrodes, and thus can be promising electrodes for VRFBs.

  2. Synthesis of new type of Au-magnetic nanocomposite and application for protein separation thereof

    Science.gov (United States)

    Song, Yu; Tao, Ling; Shen, Xiangchun

    2012-07-01

    We present a different strategy for synthesizing the Au-γ-Fe2O3 bifunctional nanoparticle by using a larger (50 nm) Au nanoparticle as the core surrounded by smaller (10 nm) γ-Fe2O3 nanoparticles. The synthesis of the composite nanoparticles is quite facile based on a simple redox process whereby Fe2+ is used to reduce Au3+. The morphology and composition of the product is measured by transmission electron microscopy, X-ray powder diffraction and UV-vis spectroscopy. We demonstrate the utility of these as-prepared Au-γ-Fe2O3 nanoparticles by showing they can be used to separate proteins in solution. For example, bovine serum is efficiently removed from an aqueous solution with the simple addition of the NPs and application of a small magnet. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis is performed to evaluate the fidelity and efficiency of the protein separation procedure.

  3. Small-molecule hydrophobic tagging-induced degradation of HaloTag fusion proteins.

    Science.gov (United States)

    Neklesa, Taavi K; Tae, Hyun Seop; Schneekloth, Ashley R; Stulberg, Michael J; Corson, Timothy W; Sundberg, Thomas B; Raina, Kanak; Holley, Scott A; Crews, Craig M

    2011-07-03

    The ability to regulate any protein of interest in living systems with small molecules remains a challenge. We hypothesized that appending a hydrophobic moiety to the surface of a protein would mimic the partially denatured state of the protein, thus engaging the cellular quality control machinery to induce its proteasomal degradation. We designed and synthesized bifunctional small molecules to bind a bacterial dehalogenase (the HaloTag protein) and present a hydrophobic group on its surface. Hydrophobic tagging of the HaloTag protein with an adamantyl moiety induced the degradation of cytosolic, isoprenylated and transmembrane HaloTag fusion proteins in cell culture. We demonstrated the in vivo utility of hydrophobic tagging by degrading proteins expressed in zebrafish embryos and by inhibiting Hras1(G12V)-driven tumor progression in mice. Therefore, hydrophobic tagging of HaloTag fusion proteins affords small-molecule control over any protein of interest, making it an ideal system for validating potential drug targets in disease models.

  4. Small-Molecule Hydrophobic Tagging Induced Degradation of HaloTag Fusion Proteins

    Science.gov (United States)

    Neklesa, Taavi K.; Tae, Hyun Seop; Schneekloth, Ashley R.; Stulberg, Michael J.; Corson, Timothy W.; Sundberg, Thomas B.; Raina, Kanak; Holley, Scott A.; Crews, Craig M.

    2011-01-01

    The ability to regulate any protein of interest in living systems with small molecules remains a challenge. We hypothesized that appending a hydrophobic moiety to the surface of a protein would mimic the partially denatured state of the protein, thus engaging the cellular quality control machinery to induce its proteasomal degradation. We designed and synthesized bifunctional small molecules that bind a bacterial dehalogenase (HaloTag protein) and present a hydrophobic group on its surface. Remarkably, hydrophobic tagging of the HaloTag protein with an adamantyl moiety induced the degradation of cytosolic, isoprenylated, and transmembrane fusion proteins in cell culture. We demonstrated the in vivo utility of hydrophobic tagging by degrading proteins expressed in zebrafish embryos and by inhibiting RasG12V-driven tumor progression in mice. Therefore, hydrophobic tagging of HaloTag fusion proteins affords small molecule control over any protein of interest, making it an ideal system for validating potential drug targets in disease models. PMID:21725302

  5. Tumor cell-selective apoptosis induction through targeting of KV10.1 via bifunctional TRAIL antibody

    Science.gov (United States)

    2011-01-01

    Background The search for strategies to target ion channels for therapeutic applications has become of increasing interest. Especially, the potassium channel KV10.1 (Ether-á-go-go) is attractive as target since this surface protein is virtually not detected in normal tissue outside the central nervous system, but is expressed in approximately 70% of tumors from different origins. Methods We designed a single-chain antibody against an extracellular region of KV10.1 (scFv62) and fused it to the human soluble TRAIL. The KV10.1-specific scFv62 antibody -TRAIL fusion protein was expressed in CHO-K1 cells, purified by chromatography and tested for biological activity. Results Prostate cancer cells, either positive or negative for KV10.1 were treated with the purified construct. After sensitization with cytotoxic drugs, scFv62-TRAIL induced apoptosis only in KV10.1-positive cancer cells, but not in non-tumor cells, nor in tumor cells lacking KV10.1 expression. In co-cultures with KV10.1-positive cancer cells the fusion protein also induced apoptosis in bystander KV10.1-negative cancer cells, while normal prostate epithelial cells were not affected when present as bystander. Conclusions KV10.1 represents a novel therapeutic target for cancer. We could design a strategy that selectively kills tumor cells based on a KV10.1-specific antibody. PMID:21899742

  6. Selective protein patterning based on the micro-structured organosilane self-assembled monolayer by vacuum ultraviolet light lithography.

    Science.gov (United States)

    Lim, Sung-Hyuk; Yamaguchi, Munehiro; Nishimura, Okio; Mie, Yasuhiro; Tamura, Tomohiro; Kim, Byung-Woo; Suzuki, Masaaki

    2009-12-01

    We have succeeded to immobilize fluorescent proteins selectively using a micro-structured organosilane self-assembled monolayer as a template. An organosilane layer with amino terminal group was formed on a thermally oxidized Si wafer by liquid-phase method and then was pattern-etched by vacuum ultraviolet light (VUV). The second organosilane layer with thiol terminal group was deposited on the etched area by chemical vapor surface modification method (CVSM). These micro-structured organosilane layer containing two reactive terminal groups were chemically modified using bi-functional linkers. Two kinds of fluorescent protein, Enhanced Cyan Fluorescent Protein (ECFP) and R-phycoerythrin were selectively immobilized on the chemically modified surface.

  7. Identification and characterization of bifunctional proline racemase/hydroxyproline epimerase from archaea: discrimination of substrates and molecular evolution.

    Directory of Open Access Journals (Sweden)

    Seiya Watanabe

    Full Text Available Proline racemase (ProR is a member of the pyridoxal 5'-phosphate-independent racemase family, and is involved in the Stickland reaction (fermentation in certain clostridia as well as the mechanisms underlying the escape of parasites from host immunity in eukaryotic Trypanosoma. Hydroxyproline epimerase (HypE, which is in the same protein family as ProR, catalyzes the first step of the trans-4-hydroxy-L-proline metabolism of bacteria. Their substrate specificities were previously considered to be very strict, in spite of similarities in their structures and catalytic mechanisms, and no racemase/epimerase from the ProR superfamily has been found in archaea. We here characterized the ProR-like protein (OCC_00372 from the hyperthermophilic archaeon, Thermococcus litoralis (TlProR. This protein could reversibly catalyze not only the racemization of proline, but also the epimerization of 4-hydroxyproline and 3-hydroxyproline with similar kinetic constants. Among the four (putative ligand binding sites, one amino acid substitution was detected between TlProR (tryptophan at the position of 241 and natural ProR (phenylalanine. The W241F mutant showed a significant preference for proline over hydroxyproline, suggesting that this (hydrophobic and bulky tryptophan residue played an importance role in the recognition of hydroxyproline (more hydrophilic and bulky than proline, and substrate specificity for hydroxyproline was evolutionarily acquired separately between natural HypE and ProR. A phylogenetic analysis indicated that such unique broad substrate specificity was derived from an ancestral enzyme of this superfamily.

  8. Cloning and characterization of a zebrafish homologue of human AQP1: a bifunctional water and gas channel

    OpenAIRE

    Chen, Li-Ming; Zhao, Jinhua; Musa-Aziz, Raif; Pelletier, Marc F.; Drummond, Iain A.; Boron, Walter F.

    2010-01-01

    The mammalian aquaporins AQP1, AQP4, and AQP5 have been shown to function not only as water channels but also as gas channels. Zebrafish have two genes encoding an AQP1 homologue, aqp1a and aqp1b. In the present study, we cloned the cDNA that encodes the zebrafish protein Aqp1a from the 72-h postfertilization (hpf) embryo of Danio rerio, as well as from the swim bladder of the adult. The deduced amino-acid sequence of aqp1a consists of 260 amino acids and is 59% identical to human AQP1. By an...

  9. Development of Guanidine-Bisurea Bifunctional Organocatalyst Bearing Chirality at the Inner and Outer Sides of the Urea Groups, and Application to Enantioselective α-Hydroxylation of Pyranoindolizine Intermediate for Camptothecin Synthesis

    Directory of Open Access Journals (Sweden)

    Minami Odagi

    2015-01-01

    Full Text Available Pyranoindolizine is a tricyclic structure found in various biologically active compounds, such as camptothecin (CPT and its derivatives. In the case of CPTs, the chirality at the α-position in the α-hydroxyl lactone moiety of pyranoindolizine is important for the antitumor activity. This paper deals with enantioselective oxidation of the α-position in pyranoindolizine lactone, which corresponds at C20 in CPT, with cumene hydroperoxide (CHP in the presence of newly synthesized guanidine-bisurea bifunctional organocatalysts bearing chirality on both the inner and outer sides of the urea groups.

  10. Advanced bifunctional electrocatalyst generated through cobalt phthalocyanine tetrasulfonate intercalated Ni2Fe-layered double hydroxides for a laminar flow unitized regenerative micro-cell

    Science.gov (United States)

    Zhong, Haihong; Tian, Ran; Gong, Xiaoman; Li, Dianqing; Tang, Pinggui; Alonso-Vante, Nicolas; Feng, Yongjun

    2017-09-01

    We fabricated a NiFeOx/CoNy-C nanocomposite derived from CoPcTs-intercalated Ni2Fe-layered double hydroxides (Ni2Fe-CoPcTs-LDH), which served as high-efficiency, low-cost, and long-durability bifunctional oxygen electrocatalyst in half-cell, and a H2-O2 laminar flow unitized regenerative micro-cell (LFURMC) in alkaline media. Based on the synergistic effect between Co-Ny and NiFeOx centers, the non-noble hybrid catalyst NiFeOx/CoNy-C achieves a ΔE (η@jOER,10 - η@jORR,-3) = 0.84 V in alkaline solution, outperforming the commercial Pt/C, and very close to that of IrOx/C. In the fuel cell mode, the performance of NiFeOx/CoNy-C with the maximum power density of 56 mW cm-2 is similar to that of Pt/C (63 mW cm-2) and IrOx/C (58 mW cm-2); in the electrolysis mode, the calculated maximum electrical power consumed on NiFeOx/CoNy-C (237 mW cm-2) is more than 3 times that on Pt/C (73 mW cm-2), similar with that of IrOx/C. More importantly, the NiFeOx/CoNy-C shows a remarkable stability in alternating modes in a LFURMC system.

  11. Related bifunctional restriction endonuclease-methyltransferase triplets: TspDTI, Tth111II/TthHB27I and TsoI with distinct specificities.

    Science.gov (United States)

    Zylicz-Stachula, Agnieszka; Zolnierkiewicz, Olga; Lubys, Arvydas; Ramanauskaite, Danute; Mitkaite, Goda; Bujnicki, Janusz M; Skowron, Piotr M

    2012-04-10

    We previously defined a family of restriction endonucleases (REases) from Thermus sp., which share common biochemical and biophysical features, such as the fusion of both the nuclease and methyltransferase (MTase) activities in a single polypeptide, cleavage at a distance from the recognition site, large molecular size, modulation of activity by S-adenosylmethionine (SAM), and incomplete cleavage of the substrate DNA. Members include related thermophilic REases with five distinct specificities: TspGWI, TaqII, Tth111II/TthHB27I, TspDTI and TsoI. TspDTI, TsoI and isoschizomers Tth111II/TthHB27I recognize different, but related sequences: 5'-ATGAA-3', 5'-TARCCA-3' and 5'-CAARCA-3' respectively. Their amino acid sequences are similar, which is unusual among REases of different specificity. To gain insight into this group of REases, TspDTI, the prototype member of the Thermus sp. enzyme family, was cloned and characterized using a recently developed method for partially cleaving REases. TspDTI, TsoI and isoschizomers Tth111II/TthHB27I are closely related bifunctional enzymes. They comprise a tandem arrangement of Type I-like domains, like other Type IIC enzymes (those with a fusion of a REase and MTase domains), e.g. TspGWI, TaqII and MmeI, but their sequences are only remotely similar to these previously characterized enzymes. The characterization of TspDTI, a prototype member of this group, extends our understanding of sequence-function relationships among multifunctional restriction-modification enzymes.

  12. Synergy of adsorption and visible-light photocatalytic degradation of methylene blue by a bifunctional Z-scheme heterojunction of WO3/g-C3N4

    Science.gov (United States)

    Liu, Xin; Jin, Ailing; Jia, Yushuai; Xia, Tonglin; Deng, Chenxin; Zhu, Meihua; Chen, Changfeng; Chen, Xiangshu

    2017-05-01

    A novel bifunctional Z-scheme heterojunction possessing high adsorption and photocatalytic activity, WO3/g-C3N4 with well-defined morphology has been successfully synthesized by in-situ liquid phase process and characterized by various analytical techniques. The degradation experiments demonstrate that the Z-scheme photocatalyst shows a synergistic effect between adsorption and photocatalysis for the removal of methylene blue (MB) under visible-light irradiation, with the optimum adsorption and photocatalytic activity both found at 30 wt% WO3/g-C3N4. Under illumination, the photodegradation performance of 30 wt% WO3/g-C3N4 is improved to 2.5 and 2.7 times that of pure g-C3N4 and pure WO3, respectively. The possible mechanism for the photocatalytic activity enhancement could be attributed to the formation of a Z-scheme heterojunction system based on the active species trapping experiments. Furthermore, the investigations of adsorption kinetics and isotherm show that the adsorption process can be well described by pseudo-second-order kinetic model, and the adsorption capacity of 30 wt% WO3/g-C3N4 is enhanced to 4 times that of pure WO3, with a maximum of 97.00 mg g-1 determined by Langmuir isotherm. As evidenced by N2 physisorption, zeta potential and time-resolved photoluminescence measurements, the significant enhancement of the integrated adsorption and photocatalytic degradation efficiency is mainly due to the synergistic advantages of large surface area, negative zeta potential and facilitated charge separation of the composite.

  13. Paclitaxel conjugated Fe3O4@LaF3:Ce3+,Tb3+ nanoparticles as bifunctional targeting carriers for Cancer theranostics application

    Science.gov (United States)

    Mangaiyarkarasi, Rajendiran; Chinnathambi, Shanmugavel; Karthikeyan, Subramani; Aruna, Prakasarao; Ganesan, Singaravelu

    2016-02-01

    The bi-functional Chitosan functionalized magnetite doped luminescent rare earth nanoparticles (Fe3O4@LaF3: Ce3+,Tb3+/chi NPs) as a carrier of paclitaxel (PTX) drug was designed using a co-precipitation and facile direct precipitation method. The synthesized nanoparticles are spherical in shape with a typical diameter of 19-37 nm respectively. They are water soluble, super paramagnetic and biocompatible, in which the amino groups on the nanoparticles surface are used for the conjugation with an anticancer drug, paclitaxel. The nature of PTX binding with Fe3O4@LaF3: Ce3+,Tb3+/chi nanoparticles were studied using X-ray diffraction, vibrating sample magnetometer and scanning electron micrograph. The nature of interactions between PTX and Fe3O4@LaF3: Ce3+,Tb3+/chi NPs due to complex formation were conceded out by various spectroscopic methods viz., UV-visible, steady state and excited state fluorescence spectroscopy. The photo-physical characterization reveals that the adsorption and release of PTX from Fe3O4@LaF3:Tb3+/chi nanoparticles is quicker when compared with other nanoparticles and also confirms that this may be due to the hydrogen bond formation between the hydroxyl group of drug and amino group of nanoparticles respectively. The maximum loading capacity and entrapment efficiency of 83.69% and 80.51% were attained at a ratio of 5:8 of PTX and Fe3O4@LaF3: Ce3+,Tb3+/chi NPs respectively. In addition with that, antitumoral activity study of PTX conjugated Fe3O4@LaF3:Tb3+/chi nanoparticles exhibits increased cytotoxic effects on A549 lung cancer cell lines than that of unconjugated PTX.

  14. Preparation of acid-base bifunctional mesoporous KIT-6 (KIT: Korea Advanced Institute of Science and Technology) and its catalytic performance in Knoevenagel reaction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ling [College of Chemistry and Chemical Engineering, Inner Mongolia University for Nationalities, Tongliao 028000 (China); Wang, Chunhua [Key Laboratory of Surface and Interface Chemistry of Jilin Province, College of Chemistry, Jilin University, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [Key Laboratory of Surface and Interface Chemistry of Jilin Province, College of Chemistry, Jilin University, Changchun 130023 (China)

    2014-05-01

    Acid-base bifunctional mesoporous catalysts Al-KIT-6-NH{sub 2} containing different aluminum content have been synthesized through post synthetic grafting method. The materials were characterized by X-ray diffraction (XRD), scanning electron micrographs (SEM), transmission electron micrographs (TEM), Fourier-transform infrared spectroscopy (FTIR), IR spectra of pyridine adsorption, NH{sub 3}-TPD and TG analysis. The characterization results indicated that the pore structure of KIT-6 was well kept after the addition of aluminum and grafting of aminopropyl groups. The acid amount of Al-KIT-6 increased with enhancing aluminum content. Catalytic results showed that weak acid and weak base favor the Knoevenagel reaction, while catalysts with strong acid and weak base exhibited worse catalytic behavior. - Graphical abstract: The postulated steps of mechanism for the acid-base catalyzed process are as follows: (1) the aldehyde gets activated by the surface acidic sites which allow the amine undergoes nucleophilic to attack the carbonyl carbon of benzaldehyde. (2) Water is released in the formation of imine intermediate. (3) The ethyl cyanoacetate reacts with the intermediate. (4) The benzylidene ethyl cyanoacetate is formed and the amine is regenerated. - Highlights: • KIT-6 and Al-KIT-6-NH{sub 2} with different Si/Al ratios has been successfully prepared. • 79.4% Yield was obtained over 46-Al-KIT-6-NH{sub 2} within 20 min in Knoevenagel reaction. • Low Al-content Al-KIT-6-NH{sub 2} shows better catalytic stability than high Al-content catalysts. • There is acid-base synergistic effect in Knoevenagel reaction.

  15. Novel bifunctional DATA chelator for quick access to site-directed PET 68Ga-radiotracers: preclinical proof-of-principle with [Tyr3]octreotide.

    Science.gov (United States)

    Nock, Berthold A; Kaloudi, Aikaterini; Nagel, Johannes; Sinnes, Jean-Philippe; Roesch, Frank; Maina, Theodosia

    2017-10-31

    Molecular imaging of tumors with the PET radionuclide 68Ga has gained momentum in clinical oncology due to the expanding availability of commercial 68Ge/68Ga-generators in combination with state-of-the-art PET/CT and PET/MRI hybrid imaging systems. Concurrently, interesting peptide-based or small-size vectors have been developed for theranostic use in cancer patients. Owing to the short half-life of 68Ga (t1/2 = 67.7 min) and the sensitivity of many targeting biomolecules, labeling and kit reconstitution in mild conditions allowing for quick access to ready-for-injection PET-tracers are highly desirable. The novel DATA ((6-pentanoic acid)-6-(amino)methy-1,4-diazepinetriacetate) chelator previously showing promising qualities for kit type labeling, was coupled to TOC ([Tyr3]octreotide). We herein report results from a first proof-of-principle study directly comparing 67Ga-DATA-TOC with the well-established 67Ga-DOTA-TOC in a series of preclinical models. Both analogs were shown to be sst2-preferring and specifically internalized in AR42J and HEK293-hsst2 cells, with 67Ga-DOTA-TOC internalizing faster in both cell lines. Similarly, after injection in mice bearing either AR42J or HEK293-hsst2 tumors, both tracers efficiently and specifically localized in the implants. Whereas 67Ga-DOTA-TOC exhibited higher tumor values, 67Ga-DATA-TOC cleared faster from background tissues. These findings support the suitability of the newly introduced bifunctional chelator DATA as a reliable, quick and convenient means for labeling medically relevant vectors with the PET radiometal 68Ga.

  16. A Novel Platinum(II)-Based Bifunctional ADC Linker Benchmarked Using 89Zr-Desferal and Auristatin F-Conjugated Trastuzumab.

    Science.gov (United States)

    Sijbrandi, Niels J; Merkul, Eugen; Muns, Joey A; Waalboer, Dennis C J; Adamzek, Kevin; Bolijn, Marije; Montserrat, Veronica; Somsen, Govert W; Haselberg, Rob; Steverink, Paul J G M; Houthoff, Hendrik-Jan; van Dongen, Guus A M S

    2017-01-15

    Greater control is desirable in the stochastic conjugation technology used to synthesize antibody-drug conjugates (ADC). We have shown recently that a fluorescent dye can be stably conjugated to a mAb using a bifunctional platinum(II) linker. Here, we describe the general applicability of this novel linker technology for the preparation of stable and efficacious ADCs. The ethylenediamine platinum(II) moiety, herein called Lx, was coordinated to Desferal (DFO) or auristatin F (AF) to provide storable "semifinal" products, which were directly conjugated to unmodified mAbs. Conjugation resulted in ADCs with unimpaired mAb-binding characteristics, DAR in the range of 2.5 to 2.7 and approximately 85% payload bound to the Fc region, presumably to histidine residues. To evaluate the in vivo stability of Lx and its effect on pharmacokinetics and tumor targeting of an ADC, Lx-DFO was conjugated to the HER2 mAb trastuzumab, followed by radiolabeling with (89)Zr. Trastuzumab-Lx-DFO-(89)Zr was stable in vivo and exhibited pharmacokinetic and tumor-targeting properties similar to parental trastuzumab. In a xenograft mouse model of gastric cancer (NCI-N87) or an ado-trastuzumab emtansine-resistant breast cancer (JIMT-1), a single dose of trastuzumab-Lx-AF outperformed its maleimide benchmark trastuzumab-Mal-AF and FDA-approved ado-trastuzumab emtansine. Overall, our findings show the potential of the Lx technology as a robust conjugation platform for the preparation of anticancer ADCs. Cancer Res; 77(2); 257-67. ©2016 AACR. ©2016 American Association for Cancer Research.

  17. Bifunctional nanocatalyst based on three-dimensional carbon nanotube-graphene hydrogel supported Pd nanoparticles: one-pot synthesis and its catalytic properties.

    Science.gov (United States)

    Zhang, Zheye; Sun, Tai; Chen, Chen; Xiao, Fei; Gong, Zheng; Wang, Shuai

    2014-12-10

    We reported the development of a new type of bifunctional nanocatalyst based on three-dimensional (3D) macroscopic carbon nanotube (CNT)-graphene hydrogel (GH) supported Pd nanoparticles (i.e., Pd-CNT-GH) and explored its practical application in catalytic reduction of p-nitrophenol to p-aminophenol. The 3D Pd-CNT-GH was synthesized by a facile one-pot self-assembled approach through hydrothermal treatment of a mixed aqueous precursor solution of PdCl4(2-), CNT, and graphene oxide (GO). Under the appropriate condition, the spontaneous redox reaction between precursor PdCl4(2-) and CNT-GO as well as the self-assembly of macroscopic CNT-GH occurs simultaneously, leading to the formation of 3D Pd-CNT-GH. Because of the unique structural and functional properties of different components in the nanocatalyst and the synergistic effect between them, the as-prepared Pd-CNT-GH exhibits superior catalytic performance toward the reduction of p-nitrophenol to p-aminophenol, with 100% conversion within 30 s, even when the content of Pd in it is as low as 2.98 wt %. Moreover, after 20 successive cycles of reactions, the reaction time still keeps within 46 s. Therefore, the rational design of 3D macroscopic graphene-based nanohybrid material supported highly catalytically active nanoparticles, combined with the facile one-pot self-assembled strategy, provide a universal platform to fabricate desired 3D multifunctional nanomaterials that can be used in a broad range of catalysis, environmental protection, energy storage and conversation, drug delivery, chemical and biological sensing, and so forth.

  18. The electron injection rate in CdSe quantum dot sensitized solar cells: from a bifunctional linker and zinc oxide morphology.

    Science.gov (United States)

    Ding, Wei-Lu; Peng, Xing-Liang; Sun, Zhu-Zhu; Li, Ze-Sheng

    2017-11-09

    Herein, we have investigated the effect of both the bifunctional linker (L1, L2, L3, and L4) and ZnO morphology (porous nanoparticles (NPs), nanowires (NWs), and nanotubes (NTs-A and NTs-Z)) on the electron injection in CdSe QD sensitized solar cells by first-principles simulation. Via calculating the partitioned interfaces formed by different components (linker/QDs and ZnO/linker), we found that the electronic states of QDs and every ZnO substrate are insensitive to any linker, while the frontier orbitals of L1-L4 (with increased delocalization) manifest a systematical negative-shift. Because of the lowest unoccupied molecular orbital (LUMO) of L1 compared to its counterparts aligned in the region of the virtual states of QDs or the substrate with a high density of states, it always yields a stronger electronic coupling with QDs and varied substrates. After characterization of the complete ZnO/linker/QD system, we found that the electron injection time (τ) vastly depends on both the linker and substrate. On the one hand, L1 bridged QDs and every substrate always achieve the shortest τ compared to their counterpart associated cases. On the other hand, NW supported systems always yield the shortest τ no matter what the linker is. Overall, the NW/L1/QD system achieves the fastest injection by ∼160 fs. This essentially stems from the shortest molecular length of L1 decreasing the distance between QDs and the substrate, subsequently improving the interfacial coupling. Meanwhile, the NW supported cases generate the less sensitive virtual states for both the QDs and NWs, ensuring a less variable interfacial coupling. These facts combined can provide understanding of the effects contributed from the linker and the oxide semiconductor morphology on charge transfer with the aim of choosing an appropriate component with fast directional electron injection.

  19. Electrochemical characterization of IrO{sub 2}-Pt and RuO{sub 2}-Pt mixtures as bifunctional electrodes for unitized regenerative fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Escalante-Garcia, I.L.; Duron-Torres, S.M. [Univ. Autonoma de Zacatecas, Zacatecas (Mexico). Unidad Academica de Ciencias Quimicas; Cruz, J.C.; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo (Mexico)

    2010-07-15

    A unitized regenerative fuel cell (URFC) is a single electrochemical cell that has the potential to meet the required features of an idealized energy cycle whereby hydrogen can be produced from renewable energy sources. A URFC is a system which can operate as a polymer electrolyte water electrolyzer (PEMWE) or as a polymer electrolyte fuel cell (PEMFC). In the PEMWE mode, water is converted into hydrogen and oxygen by using electricity from solar or wind energy. In the PEMFC mode, the stored hydrogen and oxygen are supplied to generate electricity and water. Combining PEMWEs and PEMFCs remains a great challenge because several practical and structural features must be considered. The limiting reaction steps at the oxygen electrode for PEMFC or PEMWE are the oxygen reduction reaction (ORR) and the water oxidation reaction (OER), respectively. The high-efficiency therefore depends on the type of electrocatalysts and the capability of the oxygen electrode to operate under PEMFC or PEMWE conditions. As such, much research has gone into the development of a new oxygen electrode design for URFCs. Several bifunctional electrodes for OER and ORR were designed in this study using platinum (Pt) and iridium oxide (IrO{sub 2}) electrocatalysts or Pt and ruthenium oxide (RuO{sub 2}) supported electrocatalysts on Ebonex{sup R}. According to electrochemical characterization by CV, LV and EIS in aqueous 0.5 M H{sub 2}SO{sub 4}, IrO{sub 2}-Pt and RuO{sub 2}-Pt supported on Ebonex have high electrocatalytic properties for ORR and OER, indicating potential use in URFCs. IrO{sub 2} based electrodes were more stable than RuO{sub 2} based electrodes. 31 refs., 2 tabs., 6 figs.

  20. Tailoring bifunctional hybrid organic-inorganic nanoadsorbents by the choice of functional layer composition probed by adsorption of Cu2+ ions.

    Science.gov (United States)

    Tomina, Veronika V; Melnyk, Inna V; Zub, Yuriy L; Kareiva, Aivaras; Vaclavikova, Miroslava; Seisenbaeva, Gulaim A; Kessler, Vadim G

    2017-01-01

    Spherical silica particles with bifunctional (≡Si(CH2)3NH2/≡SiCH3, ≡Si(CH2)3NH2/≡Si(CH2)2(CF2)5CF3) surface layers were produced by a one-step approach using a modified Stöber method in three-component alkoxysilane systems, resulting in greatly increased contents of functional components. The content of functional groups and thermal stability of the surface layers were analyzed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and 13C and 29Si solid-state NMR spectroscopy revealing their composition and organization. The fine chemical structure of the surface in the produced hybrid adsorbent particles and the ligand distribution were further investigated by electron paramagnetic resonance (EPR) and electron spectroscopy of diffuse reflectance (ESDR) spectroscopy using Cu2+ ion coordination as a probe. The composition and structure of the emerging surface complexes were determined and used to provide an insight into the molecular structure of the surfaces. It was demonstrated that the introduction of short hydrophobic (methyl) groups improves the kinetic characteristics of the samples during the sorption of copper(II) ions and promotes fixation of aminopropyl groups on the surface of silica microspheres. The introduction of long hydrophobic (perfluoroctyl) groups changes the nature of the surface, where they are arranged in alternately hydrophobic/hydrophilic patches. This makes the aminopropyl groups huddled and less active in the sorption of metal cations. The size and aggregation/morphology of obtained particles was optimized controlling the synthesis conditions, such as concentrations of reactants, basicity of the medium, and the process temperature.

  1. Tailoring bifunctional hybrid organic–inorganic nanoadsorbents by the choice of functional layer composition probed by adsorption of Cu2+ ions

    Directory of Open Access Journals (Sweden)

    Veronika V. Tomina

    2017-02-01

    Full Text Available Spherical silica particles with bifunctional (≡Si(CH23NH2/≡SiCH3, ≡Si(CH23NH2/≡Si(CH22(CF25CF3 surface layers were produced by a one-step approach using a modified Stöber method in three-component alkoxysilane systems, resulting in greatly increased contents of functional components. The content of functional groups and thermal stability of the surface layers were analyzed by diffuse reflectance infrared Fourier transform (DRIFT spectroscopy, and 13C and 29Si solid-state NMR spectroscopy revealing their composition and organization. The fine chemical structure of the surface in the produced hybrid adsorbent particles and the ligand distribution were further investigated by electron paramagnetic resonance (EPR and electron spectroscopy of diffuse reflectance (ESDR spectroscopy using Cu2+ ion coordination as a probe. The composition and structure of the emerging surface complexes were determined and used to provide an insight into the molecular structure of the surfaces. It was demonstrated that the introduction of short hydrophobic (methyl groups improves the kinetic characteristics of the samples during the sorption of copper(II ions and promotes fixation of aminopropyl groups on the surface of silica microspheres. The introduction of long hydrophobic (perfluoroctyl groups changes the nature of the surface, where they are arranged in alternately hydrophobic/hydrophilic patches. This makes the aminopropyl groups huddled and less active in the sorption of metal cations. The size and aggregation/morphology of obtained particles was optimized controlling the synthesis conditions, such as concentrations of reactants, basicity of the medium, and the process temperature.

  2. A minimal sequence code for switching protein structure and function.

    Science.gov (United States)

    Alexander, Patrick A; He, Yanan; Chen, Yihong; Orban, John; Bryan, Philip N

    2009-12-15

    We present here a structural and mechanistic description of how a protein changes its fold and function, mutation by mutation. Our approach was to create 2 proteins that (i) are stably folded into 2 different folds, (ii) have 2 different functions, and (iii) are very similar in sequence. In this simplified sequence space we explore the mutational path from one fold to another. We show that an IgG-binding, 4beta+alpha fold can be transformed into an albumin-binding, 3-alpha fold via a mutational pathway in which neither function nor native structure is completely lost. The stabilities of all mutants along the pathway are evaluated, key high-resolution structures are determined by NMR, and an explanation of the switching mechanism is provided. We show that the conformational switch from 4beta+alpha to 3-alpha structure can occur via a single amino acid substitution. On one side of the switch point, the 4beta+alpha fold is >90% populated (pH 7.2, 20 degrees C). A single mutation switches the conformation to the 3-alpha fold, which is >90% populated (pH 7.2, 20 degrees C). We further show that a bifunctional protein exists at the switch point with affinity for both IgG and albumin.

  3. A prion-like domain in Hsp42 drives chaperone-facilitated aggregation of misfolded proteins.

    Science.gov (United States)

    Grousl, Tomas; Ungelenk, Sophia; Miller, Stephanie; Ho, Chi-Ting; Khokhrina, Maria; Mayer, Matthias P; Bukau, Bernd; Mogk, Axel

    2018-01-23

    Chaperones with aggregase activity promote and organize the aggregation of misfolded proteins and their deposition at specific intracellular sites. This activity represents a novel cytoprotective strategy of protein quality control systems; however, little is known about its mechanism. In yeast, the small heat shock protein Hsp42 orchestrates the stress-induced sequestration of misfolded proteins into cytosolic aggregates (CytoQ). In this study, we show that Hsp42 harbors a prion-like domain (PrLD) and a canonical intrinsically disordered domain (IDD) that act coordinately to promote and control protein aggregation. Hsp42 PrLD is essential for CytoQ formation and is bifunctional, mediating self-association as well as binding to misfolded proteins. Hsp42 IDD confines chaperone and aggregase activity and affects CytoQ numbers and stability in vivo. Hsp42 PrLD and IDD are both crucial for cellular fitness during heat stress, demonstrating the need for sequestering misfolded proteins in a regulated manner. © 2018 Grousl et al.

  4. Identification of a Plastid-Localized Bifunctional Nerolidol/Linalool Synthase in Relation to Linalool Biosynthesis in Young Grape Berries

    Directory of Open Access Journals (Sweden)

    Bao-Qing Zhu

    2014-12-01

    Full Text Available Monoterpenoids are a diverse class of natural products and contribute to the important varietal aroma of certain Vitis vinifera grape cultivars. Among the typical monoterpenoids, linalool exists in almost all grape varieties. A gene coding for a nerolidol/linalool (NES/LINS synthase was evaluated in the role of linalool biosynthesis in grape berries. Enzyme activity assay of this recombinant protein revealed that it could convert geranyl diphosphate and farnesyl diphosphate into linalool and nerolidol in vitro, respectively, and thus it was named VvRILinNer. However, localization experiment showed that this enzyme was only localized to chloroplasts, which indicates that VvRILinNer functions in the linalool production in vivo. The patterns of gene expression and linalool accumulation were analyzed in the berries of three grape cultivars (“Riesling”, “Cabernet Sauvignon”, “Gewurztraminer” with significantly different levels of monoterpenoids. The VvRILinNer was considered to be mainly responsible for the synthesis of linalool at the early developmental stage. This finding has provided us with new knowledge to uncover the complex monoterpene biosynthesis in grapes.

  5. Design of an effective bifunctional catalyst organotriphosphonic acid-functionalized ferric alginate (ATMP-FA) and optimization by Box-Behnken model for biodiesel esterification synthesis of oleic acid over ATMP-FA.

    Science.gov (United States)

    Liu, Wei; Yin, Ping; Liu, Xiguang; Qu, Rongjun

    2014-12-01

    Biodiesel production has become an intense research area because of rapidly depleting energy reserves and increasing petroleum prices together with environmental concerns. This paper focused on the optimization of the catalytic performance in the esterification reaction of oleic acid for biodiesel production over the bifunctional catalyst organotriphosphonic acid-functionalized ferric alginate ATMP-FA. The reaction parameters including catalyst amount, ethanol to oleic acid molar ratio and reaction temperature have been optimized by response surface methodology (RSM) using the Box-Behnken model. It was found that the reaction temperature was the most significant factor, and the best conversion ratio of oleic acid could reach 93.17% under the reaction conditions with 9.53% of catalyst amount and 8.62:1 of ethanol to oleic acid molar ratio at 91.0 °C. The research results show that two catalytic species could work cooperatively to promote the esterification reaction, and the bifunctional ATMP-FA is a potential catalyst for biodiesel production. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Stability of a Bifunctional Cu-Based Core@Zeolite Shell Catalyst for Dimethyl Ether Synthesis Under Redox Conditions Studied by Environmental Transmission Electron Microscopy and In Situ X-Ray Ptychography.

    Science.gov (United States)

    Baier, Sina; Damsgaard, Christian D; Klumpp, Michael; Reinhardt, Juliane; Sheppard, Thomas; Balogh, Zoltan; Kasama, Takeshi; Benzi, Federico; Wagner, Jakob B; Schwieger, Wilhelm; Schroer, Christian G; Grunwaldt, Jan-Dierk

    2017-06-01

    When using bifunctional core@shell catalysts, the stability of both the shell and core-shell interface is crucial for catalytic applications. In the present study, we elucidate the stability of a CuO/ZnO/Al2O3@ZSM-5 core@shell material, used for one-stage synthesis of dimethyl ether from synthesis gas. The catalyst stability was studied in a hierarchical manner by complementary environmental transmission electron microscopy (ETEM), scanning electron microscopy (SEM) and in situ hard X-ray ptychography with a specially designed in situ cell. Both reductive activation and reoxidation were applied. The core-shell interface was found to be stable during reducing and oxidizing treatment at 250°C as observed by ETEM and in situ X-ray ptychography, although strong changes occurred in the core on a 10 nm scale due to the reduction of copper oxide to metallic copper particles. At 350°C, in situ X-ray ptychography indicated the occurrence of structural changes also on the µm scale, i.e. the core material and parts of the shell undergo restructuring. Nevertheless, the crucial core-shell interface required for full bifunctionality appeared to remain stable. This study demonstrates the potential of these correlative in situ microscopy techniques for hierarchically designed catalysts.

  7. Ru nanoparticles dispersed on magnetic yolk-shell nanoarchitectures with Fe3O4 core and sulfoacid-containing periodic mesoporous organosilica shell as bifunctional catalysts for direct conversion of cellulose to isosorbide.

    Science.gov (United States)

    Yang, Ying; Zhang, Wen; Yang, Feng; Zhou, Biao; Zeng, Dehong; Zhang, Na; Zhao, Guoming; Hao, Shijie; Zhang, Xin

    2018-01-15

    A green and sustainable approach for biorefining involves the development of bifunctional catalysts for the one-pot conversion of cellulosic biomass to isosorbide. This requires highly efficient, easily separated and versatile metal-acid catalysts for hydrolysis-hydrogenation-dehydration cascade reactions. Herein, we report a new type of metal-acid bifunctional catalyst by dispersing Ru nanoparticles (NPs) on magnetic yolk-shell nanoarchitectures comprising an Fe3O4 core and a sulfoacid (SO3H)-containing periodic mesoporous organosilica shell. The resultant magnetic Ru-SO3H nanoreactors are highly porous and have large surface areas (>350 m2 g-1), uniform mesopores (∼3.8 nm), well-dispersed Ru NPs (<1.5 wt%) and superior magnetization. Tailoring the size of the Ru NPs and the amount of SO3H moieties produced a highly efficient Ru-SO3H nanocatalyst, which delivered a high yield of isosorbide of 58.1% with almost complete conversion of cellulose in 2 h and achieved maximum productivity of 2.19 molIsosor h-1 gRu-1, which was one order of magnitude higher than that achieved using other Ru-containing acidic catalysts. Moreover, the elaborately fabricated Ru-SO3H nanocatalyst can be easily separated by applying an external magnetic field and can be cycled four times. This work reveals new possibilities for the fabrication of highly efficient, easily separated metal-acid catalysts in virtue of the concept of nanoreactor design.

  8. Atomically Thin Mesoporous Co3O4Layers Strongly Coupled with N-rGO Nanosheets as High-Performance Bifunctional Catalysts for 1D Knittable Zinc-Air Batteries.

    Science.gov (United States)

    Li, Yingbo; Zhong, Cheng; Liu, Jie; Zeng, Xiaoqiao; Qu, Shengxiang; Han, Xiaopeng; Deng, Yida; Hu, Wenbin; Lu, Jun

    2018-01-01

    Under development for next-generation wearable electronics are flexible, knittable, and wearable energy-storage devices with high energy density that can be integrated into textiles. Herein, knittable fiber-shaped zinc-air batteries with high volumetric energy density (36.1 mWh cm -3 ) are fabricated via a facile and continuous method with low-cost materials. Furthermore, a high-yield method is developed to prepare the key component of the fiber-shaped zinc-air battery, i.e., a bifunctional catalyst composed of atomically thin layer-by-layer mesoporous Co 3 O 4 /nitrogen-doped reduced graphene oxide (N-rGO) nanosheets. Benefiting from the high surface area, mesoporous structure, and strong synergetic effect between the Co 3 O 4 and N-rGO nanosheets, the bifunctional catalyst exhibits high activity and superior durability for oxygen reduction and evolution reactions. Compared to a fiber-shaped zinc-air battery using state-of-the-art Pt/C + RuO 2 catalysts, the battery based on these Co 3 O 4 /N-rGO nanosheets demonstrates enhanced and stable electrochemical performance, even under severe deformation. Such batteries, for the first time, can be successfully knitted into clothes without short circuits under external forces and can power various electronic devices and even charge a cellphone. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Controlled growth, intense upconversion emissions and concentration induced luminescence switching of bifunctional Tm3+ doped hexagonal NaYb0.55Gd0.45F4 nanorods

    Science.gov (United States)

    Qu, Xilong; Li, Yongchang; Yu, Suixi; Yang, Liwen

    2013-11-01

    Bifunctional hexagonal Tm3+ doped NaYb0.55Gd0.45F4 nanorods with tunable size are prepared via in situ cation-exchange reaction using hydrothermal method. The measured field dependence of magnetization of the NaYb0.55Gd0.45F4 nanorods shows typical paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of rare-earth ions. When excited by a 980 nm laser, these nanorods exhibit intense multi-color up-conversion (UC) emissions in infrared, red, blue and especially ultraviolet. In addition, luminescent switching between different UC emission wavelengths of 480 nm and 450 nm is observed by adjusting Tm3+ doping concentration. Based on power-dependent spectral analyses, it is found that with the increase of Tm3+ doping concentration, due to the suppressed saturation effect, the dominative UC process redistribute the populations at 1G4 and 1D2(Tm3+) states of Tm3+ ion resulting in the above luminescent switching. Our results indicate that bifunctional hexagonal NaYb1-xGdxF4 nanocrystals have potential applications in miniaturized solid-state light sources, optical processing sensors and fluorescent biolabels.

  10. Pilot-scale cultivation of wall-deficient transgenic Chlamydomonas reinhardtii strains expressing recombinant proteins in the chloroplast

    DEFF Research Database (Denmark)

    Zedler, Julie A.Z.; Gangl, Doris; Guerra, Tiago

    2016-01-01

    Microalgae have emerged as potentially powerful platforms for the production of recombinant proteins and high-value products. Chlamydomonas reinhardtii is a potentially important host species due to the range of genetic tools that have been developed for this unicellular green alga. Transformation...... growth data for C. reinhardtii grown at pilot scale, and the growth of cell wall-deficient strains has not been reported at all. Here, we report the first pilot-scale growth study for transgenic, cell wall-deficient C. reinhardtii strains. Strains expressing a cytochrome P450 (CYP79A1) or bifunctional...... diterpene synthase (cis-abienol synthase, TPS4) were grown for 7 days under mixotrophic conditions in a Tris-acetate-phosphate medium. The strains reached dry cell weights of 0.3 g/L within 3–4 days with stable expression levels of the recombinant proteins during the whole upscaling process. The strains...

  11. Cloning and characterization of a zebrafish homologue of human AQP1: a bifunctional water and gas channel.

    Science.gov (United States)

    Chen, Li-Ming; Zhao, Jinhua; Musa-Aziz, Raif; Pelletier, Marc F; Drummond, Iain A; Boron, Walter F

    2010-11-01

    The mammalian aquaporins AQP1, AQP4, and AQP5 have been shown to function not only as water channels but also as gas channels. Zebrafish have two genes encoding an AQP1 homologue, aqp1a and aqp1b. In the present study, we cloned the cDNA that encodes the zebrafish protein Aqp1a from the 72-h postfertilization (hpf) embryo of Danio rerio, as well as from the swim bladder of the adult. The deduced amino-acid sequence of aqp1a consists of 260 amino acids and is 59% identical to human AQP1. By analyzing the genomic DNA sequence, we identified four exons in the aqp1a gene. By in situ hybridization, aqp1a is expressed transiently in the developing vasculature and in erythrocytes from 16 to 48 h of development. Later, at 72 hpf, aqp1a is expressed in dermal ionocytes and in the swim bladder. Western blot analysis of adult tissues reveals that Aqp1a is most highly expressed in the eye and swim bladder. Xenopus oocytes expressing aqp1a have a channel-dependent (*) osmotic water permeability (P(f)(*)) that is indistinguishable from that of human AQP1. On the basis of the magnitude of the transient change in surface pH (ΔpH(S)) that were recorded as the oocytes were exposed to either CO(2) or NH(3), we conclude that zebrafish Aqp1a is permeable to both CO(2) and NH(3). The ratio (ΔpH(S)(*))((CO)2)/P(f)(*) is about half that of human AQP1, and the ratio (ΔpH(S)(*))(NH3)/P(f)(*) is about one-quarter that of human AQP1. Thus, compared with human AQP1, zebrafish Aqp1a has about twice the selectivity for CO(2) over NH(3).

  12. A novel glycoside hydrolase family 97 enzyme: Bifunctional β-l-arabinopyranosidase/α-galactosidase from Bacteroides thetaiotaomicron.

    Science.gov (United States)

    Kikuchi, Asako; Okuyama, Masayuki; Kato, Koji; Osaki, Shohei; Ma, Min; Kumagai, Yuya; Matsunaga, Kana; Klahan, Patcharapa; Tagami, Takayoshi; Yao, Min; Kimura, Atsuo

    2017-11-01

    Glycoside hydrolase family 97 (GH97) is one of the most interesting glycosidase families, which contains inverting and retaining glycosidases. Currently, only two enzyme types, α-glucoside hydrolase and α-galactosidase, are registered in the carbohydrate active enzyme database as GH97 function-known proteins. To explore new specificities, BT3661 and BT3664, which have distinct amino acid sequences when compared with that of GH97 α-glucoside hydrolase and α-galactosidase, were characterized in this study. BT3664 was identified to be an α-galactosidase, whereas BT3661 exhibits hydrolytic activity toward both β-l-arabinopyranoside and α-d-galactopyranoside, and thus we designate BT3661 as a β-l-arabinopyranosidase/α-d-galactosidase. Since this is the first dual substrate specificity enzyme in GH97, we investigated the substrate recognition mechanism of BT3661 by determining its three-dimensional structure and based on this structural data generated a number of mutants to probe the enzymatic mechanism. Structural comparison shows that the active-site pocket of BT3661 is similar to GH97 α-galactosidase BT1871, but the environment around the hydroxymethyl group of the galactopyranoside is different. While BT1871 bears Glu361 to stabilize the hydroxy group of C6 through a hydrogen bond with its carboxy group, BT3661 has Asn338 at the equivalent position. Amino acid mutation analysis indicates that the length of the side chain at Asn338 is important for defining specificity of BT3661. The k cat /K m value for the hydrolysis of p-nitrophenyl α-galactoside decreases when Asn338 is substituted with Glu, whereas an increase is observed when the mutation is Ala. Interestingly, mutation of Asn338 to Ala reduces the k cat /K m value for hydrolysis of p-nitrophenyl β-l-arabinopyranoside. Copyright © 2017. Published by Elsevier B.V.

  13. Barley alpha-amylase/subtilisin inhibitor: structure, biophysics and protein engineering

    DEFF Research Database (Denmark)

    Nielsen, P.K.; Bønsager, Birgit Christine; Fukuda, Kenji

    2004-01-01

    -type trypsin inhibitor family of the beta-trefoil fold proteins. Diverse approaches including site-directed mutagenesis, hybrid constructions, and crystallography have been used to characterise the structures and contact residues in the AMY2/BASI complex. The three-dimensional structure of the AMY2/BASI......Bifunctional alpha-amylase/subtilisin inhibitors have been implicated in plant defence and regulation of endogenous alpha-amylase action. The barley alpha-amylase/subtilisin inhibitor (BASI) inhibits the barley alpha-amylase 2 (AMY2) and subtilisin-type serine proteases. BASI belongs to the Kunitz...... Ca2+-modulated kinetics of the AMY2/BASl interaction and found that the complex formation involves minimal structural changes. The modulation of the interaction by calcium ions makes it unique among the currently known binding mechanisms of proteinaceous alpha-amylase inhibitors....

  14. Bifunctional ferromagnetic Eu-Gd-Bi-codoped hybrid organo-silica red emitting phosphors synthesized by a modified Pechini sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Abo-Naf, S.M., E-mail: sm.abo-naf@nrc.sci.eg [Glass Research Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt); Abdel-Hameed, S.A.M.; Marzouk, M.A. [Glass Research Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt); Hamdy, Y.M. [Spectroscopy Department, National Research Centre (NRC), El-Buhouth Str., Dokki, 12622 Cairo (Egypt)

    2017-06-15

    Red phosphor, composed of Eu-Gd-Bi-codoped hybrid organo-silica glass, has been synthesized via a modified Pechini sol-gel process. The synthesized hybrid glass was analyzed with powder X-ray diffraction (XRD), differential thermal analysis coupled with thermogravimetry (DTA-TG) and Fourier transform infrared (FTIR) spectroscopy. XRD and DTA-TG confirmed its amorphous structure up to 1000 °C. Magnetic behavior of the produced phosphor was investigated using vibrating specimen magnetometer (VSM) and the obtained results revealed its unsaturated ferromagnetic behavior. Photoluminescence (PL) properties of the obtained phosphor have been investigated under near-UV excitation at 395 nm. The influence of calcination temperature on the PL intensity and its decay behavior as well as on the ferromagnetic characteristics has been studied to determine the optimal reaction temperature of the phosphor. The PL emission spectra show the characteristic emission bands of Eu{sup 3+} ions in the wavelength range from 580 to 700 nm. These emission spectra have been dominated by the electric dipole {sup 5}D{sub 0}→{sup 7}F{sub 2} transition of the Eu{sup 3+} peaked at 610–620 nm producing the red light emission of the phosphors. It was found that the phosphor performance, expressed by its PL intensity and life time, could be significantly improved by increasing of the heat treatment temperature up to 900 °C. Also, calcination at 900 °C for 6 h greatly increased both of the magnetization and retentivity, while decreased the coercivity value. The organic phenomenon of metal citrate-ethylene glycol chelation and its degradation by calcination were well followed by FTIR spectroscopy. The obtained results are promising and could afford a basis for designing of efficient red phosphors for displays, lighting and bifunctional biosensors for biomedical applications. - Highlights: • Eu-Gd-Bi-codoped hybrid organo-silica phosphor was synthesized by sol-gel method. • Inorganic Eu

  15. KatG, the Bifunctional Catalase of Xanthomonas citri subsp. citri, Responds to Hydrogen Peroxide and Contributes to Epiphytic Survival on Citrus Leaves.

    Directory of Open Access Journals (Sweden)

    María Laura Tondo

    Full Text Available Xanthomonas citri subsp. citri (Xcc is the bacterium responsible for citrus canker. This bacterium is exposed to reactive oxygen species (ROS at different points during its life cycle, including those normally produced by aerobic respiration or upon exposition to ultraviolet (UV radiation. Moreover, ROS are key components of the host immune response. Among enzymatic ROS-detoxifying mechanisms, catalases eliminate H2O2, avoiding the potential damage caused by this specie. Xcc genome includes four catalase genes. In this work, we studied the physiological role of KatG, the only bifunctional catalase of Xcc, through the construction and characterization of a modified strain (XcckatG, carrying an insertional mutation in the katG gene. First, we evaluated the involvement of KatG in the bacterial adaptive response to H2O2. XcckatG cultures exhibited lower catalase activity than those of the wild-type strain, and this activity was not induced upon treatment with sub-lethal doses of H2O2. Moreover, the KatG-deficient mutant exhibited decreased tolerance to H2O2 toxicity compared to wild-type cells and accumulated high intracellular levels of peroxides upon exposure to sub-lethal concentrations of H2O2. To further study the role of KatG in Xcc physiology, we evaluated bacterial survival upon exposure to UV-A or UV-B radiation. In both conditions, XcckatG showed a high mortality in comparison to Xcc wild-type. Finally, we studied the development of bacterial biofilms. While structured biofilms were observed for the Xcc wild-type, the development of these structures was impaired for XcckatG. Based on these results, we demonstrated that KatG is responsible for Xcc adaptive response to H2O2 and a key component of the bacterial response to oxidative stress. Moreover, this enzyme plays an important role during Xcc epiphytic survival, being essential for biofilm formation and UV resistance.

  16. L-Malyl-coenzyme A lyase/beta-methylmalyl-coenzyme A lyase from Chloroflexus aurantiacus, a bifunctional enzyme involved in autotrophic CO(2) fixation.

    Science.gov (United States)

    Herter, Sylvia; Busch, Andreas; Fuchs, Georg

    2002-11-01

    The 3-hydroxypropionate cycle is a bicyclic autotrophic CO(2) fixation pathway in the phototrophic Chloroflexus aurantiacus (Bacteria), and a similar pathway is operating in autotrophic members of the Sulfolobaceae (Archaea). The proposed pathway involves in a first cycle the conversion of acetyl-coenzyme A (acetyl-CoA) and two bicarbonates to L-malyl-CoA via 3-hydroxypropionate and propionyl-CoA; L-malyl-CoA is cleaved by L-malyl-CoA lyase into acetyl-CoA and glyoxylate. In a second cycle, glyoxylate and another molecule of propionyl-CoA (derived from acetyl-CoA and bicarbonate) are condensed by a putative beta-methylmalyl-CoA lyase to beta-methylmalyl-CoA, which is converted to acetyl-CoA and pyruvate. The putative L-malyl-CoA lyase gene of C. aurantiacus was cloned and expressed in Escherichia coli, and the recombinant enzyme was purified and studied. Beta-methylmalyl-CoA lyase was purified from cell extracts of C. aurantiacus and characterized. We show that these two enzymes are identical and that both enzymatic reactions are catalyzed by one single bifunctional enzyme, L-malyl-CoA lyase/beta-methylmalyl-CoA lyase. Interestingly, this enzyme works with two different substrates in two different directions: in the first cycle of CO(2) fixation, it cleaves L-malyl-CoA into acetyl-CoA and glyoxylate (lyase reaction), and in the second cycle it condenses glyoxylate with propionyl-CoA to beta-methylmalyl-CoA (condensation reaction). The combination of forward and reverse directions of a reversible enzymatic reaction, using two different substrates, is rather uncommon and reduces the number of enzymes required in the pathway. In summary, L-malyl-CoA lyase/beta-methylmalyl-CoA lyase catalyzes the interconversion of L-malyl-CoA plus propionyl-CoA to beta-methylmalyl-CoA plus acetyl-CoA.

  17. Electroanalytical Assessment of the Effect of Ni:Fe Stoichiometry and Architectural Expression on the Bifunctional Activity of Nanoscale NiyFe1-yOx.

    Science.gov (United States)

    Ko, Jesse S; Chervin, Christopher N; Vila, Mallory N; DeSario, Paul A; Parker, Joseph F; Long, Jeffrey W; Rolison, Debra R

    2017-09-19

    Electrocatalysis of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was assessed for a series of Ni-substituted ferrites (Ni y Fe 1-y Ox, where y = 0.1 to 0.9) as expressed in porous, high-surface-area forms (ambigel and aerogel nanoarchitectures). We then correlate electrocatalytic activity with Ni:Fe stoichiometry as a function of surface area, crystallite size, and free volume. In order to ensure in-series comparisons, calcination at 350 °C/air was necessary to crystallize the respective Ni y Fe 1-y Ox nanoarchitectures, which index to the inverse spinel structure for Fe-rich materials (y ≤ 0.33), rock salt for the most Ni-rich material (y = 0.9), and biphasic for intermediate stoichiometry (0.5 ≤ y ≤ 0.67). In the intermediate Ni:Fe stoichiometric range (0.33 ≤ y ≤ 0.67), the OER current density at 390 mV increases monotonically with increasing Ni content and increasing surface area, but with different working curves for ambigels versus aerogels. At a common stoichiometry within this range, ambigels and aerogels yield comparable OER performance, but do so by expressing larger crystallite size (ambigel) versus higher surface area (aerogel). Effective OER activity can be achieved without requiring supercritical-fluid extraction as long as moderately high surface area, porous materials can be prepared. We find improved OER performance (η decreases from 390 to 373 mV) for Ni 0.67 Fe 0.33 Ox aerogel heat-treated at 300 °C/Ar, owing to an increase in crystallite size (2.7 to 4.1 nm). For the ORR, electrocatalytic activity favors Fe-rich Ni y Fe 1-y Ox materials; however, as the Ni-content increases beyond y = 0.5, a two-electron reduction pathway is still exhibited, demonstrating that bifunctional OER and ORR activity may be possible by choosing a nickel ferrite nanoarchitecture that provides high OER activity with sufficient ORR activity. Assessing the catalytic activity requires an appreciation of the multivariate interplay

  18. Heterometallic Alkaline Earth-Lanthanide Ba(II)-La(III) Microporous Metal-Organic Framework as Bifunctional Luminescent Probes of Al(3+) and MnO4(.).

    Science.gov (United States)

    Ding, Bin; Liu, Shi Xin; Cheng, Yue; Guo, Chao; Wu, Xiang Xia; Guo, Jian Hua; Liu, Yuan Yuan; Li, Yan

    2016-05-02

    In this work a rigid asymmetrical tricarboxylate ligand p-terphenyl-3,4″,5-tricarboxylic acid (H3L) has been employed, and a unique heterometallic alkaline earth-lanthanide microporous luminescent metal-organic framework (MOF) {[Ba3La0.5(μ3-L)2.5(H2O)3(DMF)]·(3DMF)}n (1·3DMF) (DMF = dimethylformamide) has been isolated under solvothermal conditions. Single-crystal X-ray structural analysis demonstrates that 2D inorganic Ba-O-La connectivity can be observed in 1, which are further bridged via rigid terphenyl backbones of L(3-), forming a unique I(2)O(1)-type microporous luminescent framework. A 1D microporous channel with dimensionality of 9.151(3) Å × 10.098(1) Å can be observed along the crystallographic a axis. PXRD patterns have been investigated indicating pure phases of 1. The luminescence explorations demonstrated that 1 exhibits highly selective and sensitive sensing for Al(3+) over other cations with high quenching efficiency Ksv value of 1.445 × 10(4) L·mol(-1) and low detection limit (1.11 μM (S/N = 3)). Meanwhile 1 also exhibits highly selective and sensitive sensing for MnO4(-) over other anions with quenching efficiency Ksv = 7.73 × 10(3) L·mol(-1) and low detection limit (0.28 μM (S/N = 3)). It is noted that, when different concentrations of MnO4(-) solutions (0.5 to 100 μM) were dropped into the suspension of 1, the bright blue luminescence of the suspension observed under UV light can gradually change into pink color, indicating visually luminescent sensing, which makes the detection process of MnO4(-) more convenient in practical. The result also reveals that 1 represents the first example of bifunctional heterometallic alkaline earth-lanthanide MOF-based luminescent probes for selectively detecting Al(3+) and MnO4(-) in the water solutions.

  19. Top-down synthesis of versatile polyaspartamide linkers for single-step protein conjugation to materials.

    Science.gov (United States)

    Cha, Chaenyung; Jeong, Jae Hyun; Tang, Xin; Zill, Andrew T; Prakash, Y S; Zimmerman, Steven C; Saif, Taher A; Kong, Hyunjoon

    2011-12-21

    Materials used in various biological applications are often modified with proteins to regulate biomolecular and cellular adhesion. Conventional strategies of protein conjugation accompany monovalent bifunctional protein linkers, which present several limitations in molecular synthesis and protein conjugation. Herein, we present a new strategy of preparing multivalent polyaspartamide linkers in a simple top-down manner, and also demonstrate that the resulting polymer linkers allow us to readily conjugate proteins to both organic and inorganic materials. The top-down synthesis of polyaspartamide linkers was performed by partially opening succinimidyl ring moieties of polysuccinimide (PSI) with the controlled number of nucleophiles reactive to photo-cross-linked hydrogel or gold-coated inorganic materials: (1) Poly(2-hydroxyethyl-co-2-methacryloxyethyl aspartamide) (PHMAA) presenting methacrylate was used to micropattern fibronectin or collagen on a hydrogel in order to regulate cell adhesion and growth area on a micrometer scale. (2) Poly(2-hydroxyethyl-co-2-mercaptoethyl aspartamide) (PHMCA) presenting thiol functional groups was used to link fibronectin to a gold-coated silicon microelectromechanical probe designed to measure cell traction force. Overall, these multivalent polyaspartamide protein linkers will greatly assist efforts to analyze and regulate the cellular adhesion to and phenotypic activities of a wide array of substrates and devices.

  20. Total protein

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003483.htm Total protein To use the sharing features on this page, please enable JavaScript. The total protein test measures the total amount of two classes ...

  1. Protein Structure

    Science.gov (United States)

    Asmus, Elaine Garbarino

    2007-01-01

    Individual students model specific amino acids and then, through dehydration synthesis, a class of students models a protein. The students clearly learn amino acid structure, primary, secondary, tertiary, and quaternary structure in proteins and the nature of the bonds maintaining a protein's shape. This activity is fun, concrete, inexpensive and…

  2. Fe{sub 2.25}W{sub 0.75}O{sub 4}/reduced graphene oxide nanocomposites for novel bifunctional photocatalyst: One-pot synthesis, magnetically recyclable and enhanced photocatalytic property

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jinxue; Jiang, Bin; Zhang, Xiao, E-mail: zhx1213@126.com; Zhou, Xiaoyu; Hou, Wanguo

    2013-09-15

    Fe{sub 2.25}W{sub 0.75}O{sub 4}/reduced graphene oxide (RGO) composites were prepared for application of novel bifunctional photocatalyst via simple one-pot hydrothermal method, employing graphene oxide (GO), Na{sub 2}WO{sub 4}, FeSO{sub 4} and sodium dodecyl benzene sulfonate (SDBS) as the precursors. Transmission electron microscope (TEM) results indicate that the well-dispersed Fe{sub 2.25}W{sub 0.75}O{sub 4} nanoparticles were deposited on the surface of RGO sheets homogeneously. Magnetic characterization reveals that Fe{sub 2.25}W{sub 0.75}O{sub 4} and Fe{sub 2.25}W{sub 0.75}O{sub 4}/RGO show ferromagnetic behaviors. So this novel bifunctional photocatalyst could achieve magnetic separation and collection with the aid of external magnet. The composites exhibit enhanced photocatalytic performance on degradation of methyl orange (MO) compared with pure Fe{sub 2.25}W{sub 0.75}O{sub 4} under low-power ultraviolet light irradiation due to the introduction of RGO. Moreover, this hybrid catalyst possesses long-term excellent photocatalytic performance due to its good thermal stability. This bifunctional photocatalyst, which combines magnetic property and excellent photocatalytic activity, would be a perfect candidate in applications of catalytic elimination of environmental pollutants and other areas. - Graphical abstract: Magnetically recyclable Fe{sub 2.25}W{sub 0.75}O{sub 4}/reduced graphene oxide nanocomposites with enhanced photocatalytic property Display Omitted - Highlights: ●Fe{sub 2.25}W{sub 0.75}O{sub 4} growth, deposition and GO reduction occurred simultaneously. ●Composite possessed ferromagnetic and enhanced photocatalytic properties. ●Composite is utilized as a magnetically separable and high-efficient photocatalyst. ●Photocatalyst showed good photocatalytic and thermal stability during cyclic use.

  3. Study of the hydro-isomerization of paraffins with 7 and 8 carbon atoms on bifunctional catalysts; Etude de l'hydroisomerisation des paraffines a 7 et 8 atomes de carbone sur catalyseurs bifonctionnels

    Energy Technology Data Exchange (ETDEWEB)

    Patrigeon, A.

    2000-10-11

    Due to the suppression of lead additives and the trend to decrease the aromatic and olefinic content in gasoline, the interest for new octane enhancement processes has increased, particularly for isomerization of C{sub 7} and C{sub 8} linear paraffins into higher octane number multi-branched paraffins. Up to the present day, no industrial bifunctional catalyst exists due to the high tendency of the paraffins to be cracked limiting the amount of multi-branched products. The aim of this work is to study the possibility of isomerizing linear C{sub 7} and C{sub 8} paraffins in two steps in order to increase the amount of formed multi-branched paraffins. The first step converts linear paraffins into mono-branched paraffins (that step is supposed to be the slowest one) carried out using one bifunctional catalyst. The second step converts the formed mono-branched paraffins into multi-branched paraffins using a second bifunctional catalyst. The aim is to determine the characteristics of the two catalysts. To study the first step, Pt/zeolite or Pt/meso-porous solid catalysts, with different acidities and porosities, were tested in n-heptane and n-octane hydro-conversion. The role of solid porosity on selectivities was clearly established. Molecular modelling was utilised to explain the observed selectivities. To study the second step, the 2-methyl-hexane and 2-methyl-heptane hydro-conversion on Pt/H-beta and Pt/H-Y was carried out. This lead to maximum multi-branched yields similar to those obtained with the n-heptane and n-octane hydro-conversion. That result shows that the two steps isomerization process is not necessarily required because no more multi-branched products are formed. A kinetic study on the n-heptane hydro-conversion was performed. The decomposition of isomerization and cracking reactions into elementary steps has shown the major role of the paraffins physio-sorption step in the zeolite pores. (author)

  4. 3D hollow sphere Co3O4/MnO2-CNTs: Its high-performance bi-functional cathode catalysis and application in rechargeable zinc-air battery

    Directory of Open Access Journals (Sweden)

    Xuemei Li

    2017-07-01

    Full Text Available There has been a continuous need for high active, excellently durable and low-cost electrocatalysts for rechargeable zinc-air batteries. Among many low-cost metal based candidates, transition metal oxides with the CNTs composite have gained increasing attention. In this paper, the 3-D hollow sphere MnO2 nanotube-supported Co3O4 nanoparticles and its carbon nanotubes hybrid material (Co3O4/MnO2-CNTs have been synthesized via a simple co-precipitation method combined with post-heat treatment. The morphology and composition of the catalysts are thoroughly analyzed through SEM, TEM, TEM-mapping, XRD, EDX and XPS. In comparison with the commercial 20% Pt/C, Co3O4/MnO2, bare MnO2 nanotubes and CNTs, the hybrid Co3O4/MnO2-CNTs-350 exhibits perfect bi-functional catalytic activity toward oxygen reduction reaction and oxygen evolution reaction under alkaline condition (0.1 M KOH. Therefore, high cell performances are achieved which result in an appropriate open circuit voltage (∼1.47 V, a high discharge peak power density (340 mW cm−2 and a large specific capacity (775 mAh g−1 at 10 mA cm−2 for the primary Zn-air battery, a small charge–discharge voltage gap and a high cycle-life (504 cycles at 10 mA cm−2 with 10 min per cycle for the rechargeable Zn-air battery. In particular, the simple synthesis method is suitable for a large-scale production of this bifunctional material due to a green, cost effective and readily available process. Keywords: Bi-functional catalyst, Oxygen reduction reaction, Oxygen evolution reaction, Activity and stability, Rechargeable zinc-air battery

  5. Structural Basis for a Ribofuranosyl Binding Protein: Insights into the Furanose Specific Transport

    Energy Technology Data Exchange (ETDEWEB)

    Bagaria, A.; Swaminathan, S.; Kumaran, D.; Burley, S. K.

    2011-04-01

    The ATP-binding cassette transporters (ABC-transporters) are members of one of the largest protein superfamilies, with representatives in all extant phyla. These integral membrane proteins utilize the energy of ATP hydrolysis to carry out certain biological processes, including translocation of various substrates across membranes and non-transport related processes such as translation of RNA and DNA repair. Typically, such transport systems in bacteria consist of an ATP binding component, a transmembrane permease, and a periplasmic receptor or binding protein. Soluble proteins found in the periplasm of gram-negative bacteria serve as the primary receptors for transport of many compounds, such as sugars, small peptides, and some ions. Ligand binding activates these periplasmic components, permitting recognition by the membrane spanning domain, which supports for transport and, in some cases, chemotaxis. Transport and chemotaxis processes appear to be independent of one another, and a few mutants of bifunctional periplasmic components reveal the absence of one or the other function. Previously published high-resolution X-ray structures of various periplasmic ligand binding proteins include Arabinose binding protein (ABP), Allose binding protein (ALBP), Glucose-galactose binding protein (GBP) and Ribose binding protein (RBP). Each of these proteins consists of two structurally similar domains connected by a three-stranded hinge region, with ligand buried between the domains. Upon ligand binding and release, various conformational changes have been observed. For RBP, open (apo) and closed (ligand bound) conformations have been reported and so for MBP. The closed/active form of the protein interacts with the integral membrane component of the system in both transport and chemotaxis. Herein, we report 1.9{angstrom} resolution X-ray structure of the R{sub f}BP periplasmic component of an ABC-type sugar transport system from Hahella chejuensis (UniProt Id Q2S7D2) bound to

  6. Structural Basis for a Ribofuranosyl Binding Protein: Insights into the Furanose Specific Transport

    Energy Technology Data Exchange (ETDEWEB)

    A Bagaria; D Kumaran; S Burley; S Swaminathan

    2011-12-31

    The APT-binding cassette transporters (ABC-transporters) are members of one of the largest protein superfamilies, with representatives in all extant phyla. These integral membrane proteins utilize the energy of ATP hydrolysis to carry out certain biological processes, including translocation of various substrates across membranes and nontransport related processes such as translation of RNA and DNA repair. typically, such transport systems in bacteria consist of an ATP binding component, a transmembrane permease, and a periplasmic receptor or binding protein. Soluble proteins found in the periplasm of gram-negative bacteria serve as the primary receptors for transport of many compounds, such as sugars, small peptides, and some ions. Ligand binding activates these periplasmic components, permitting recognition by the membrane spanning domain, which supports for transport, and, in some cases, chemotaxis. Transport and chemotaxis processes appear to be independent of one another, and a few mutants of bifunctional periplasmic components reveal the absence of one or the other function. Previously published high-resolution X-ray structures of various periplasmic ligand binding proteins include Arabinose binding protein (ABP), Allose binding protein (ALBP), Glucose-galactose binding protein (GBP), and Ribose binding protein (RBP). Each of these proteins consits of two structurally similar domains connected by a three-stranded hinge region, with ligand buried between the domains. Upon ligand binding and release, various conformational changes have been observed. For RBP, open (apo) and closed (ligand bound) conformations hafve been reported and so for MBP. The closed/active form of the protein interacts with the ingral membrane component of the system in both transport and chemotaxis. Herein, they report 1.9 {angstrom} resolution X-ray structure of the R{sub f}BP periplasmic component of an ABC-type sugar transport system from Hahella chejuensis (UniProt Id Q2S7D2) bound

  7. Chemical approaches to targeted protein degradation through modulation of the ubiquitin-proteasome pathway.

    Science.gov (United States)

    Collins, Ian; Wang, Hannah; Caldwell, John J; Chopra, Raj

    2017-03-15

    Manipulation of the ubiquitin-proteasome system to achieve targeted degradation of proteins within cells using chemical tools and drugs has the potential to transform pharmacological and therapeutic approaches in cancer and other diseases. An increased understanding of the molecular mechanism of thalidomide and its analogues following their clinical use has unlocked small-molecule modulation of the substrate specificity of the E3 ligase cereblon (CRBN), which in turn has resulted in the advancement of new immunomodulatory drugs (IMiDs) into the clinic. The degradation of multiple context-specific proteins by these pleiotropic small molecules provides a means to uncover new cell biology and to generate future drug molecules against currently undruggable targets. In parallel, the development of larger bifunctional molecules that bring together highly specific protein targets in complexes with CRBN, von Hippel-Lindau, or other E3 ligases to promote ubiquitin-dependent degradation has progressed to generate selective chemical compounds with potent effects in cells and in vivo models, providing valuable tools for biological target validation and with future potential for therapeutic use. In this review, we survey recent breakthroughs achieved in these two complementary methods and the discovery of new modes of direct and indirect engagement of target proteins with the proteasome. We discuss the experimental characterisation that validates the use of molecules that promote protein degradation as chemical tools, the preclinical and clinical examples disclosed to date, and the future prospects for this exciting area of chemical biology. © 2017 The Author(s).

  8. The F-plasmid TraI protein contains three functional domains required for conjugative DNA strand transfer.

    Science.gov (United States)

    Matson, Steven W; Ragonese, Heather

    2005-01-01

    The F-plasmid-encoded TraI protein, also known as DNA helicase I, is a bifunctional protein required for conjugative DNA transfer. The enzyme catalyzes two distinct but functionally related reactions required for the DNA processing events associated with conjugation: the site- and strand-specific transesterification (relaxase) reaction that provides the nick required to initiate strand transfer and a processive 5'-to-3' helicase reaction that provides the motive force for strand transfer. Previous studies have identified the relaxase domain, which encompasses the first approximately 310 amino acids of the protein. The helicase-associated motifs lie between amino acids 990 and 1450. The function of the region between amino acids 310 and 990 and the region from amino acid 1450 to the C-terminal end is unknown. A protein lacking the C-terminal 252 amino acids (TraIDelta252) was constructed and shown to have essentially wild-type levels of transesterase and helicase activity. In addition, the protein was capable of a functional interaction with other components of the minimal relaxosome. However, TraIDelta252 was not able to support conjugative DNA transfer in genetic complementation experiments. We conclude that TraIDelta252 lacks an essential C-terminal domain that is required for DNA transfer. We speculate this domain may be involved in essential protein-protein interactions with other components of the DNA transfer machinery.

  9. Single-step synthesis of DME from syngas on Cu-ZnO-Al{sub 2}O{sub 3}/zeolite bifunctional catalysts: The superiority of ferrierite over the other zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Sai Prasad, P.S.; Bae, Jong Wook; Kang, Suk-Hwan; Lee, Yun-Jo; Jun, Ki-Won [Alternative Chemicals/Fuel Research Center, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Sinseongno 19, Yuseong, Daejeon 305-600 (Korea)

    2008-12-15

    Single-step synthesis of DME was studied on four different bifunctional catalysts containing Cu-ZnO-Al{sub 2}O{sub 3} as the common methanol synthesis component and ferrierite, ZSM-5, NaY or HY, as the solid acid component. The catalysts were prepared by co-precipitation of the metallic component in the slurry of the zeolite, and were characterized by nitrogen adsorption, XRD and ammonia TPD. Cu-ZnO-Al{sub 2}O{sub 3}/ferrierite is found to be superior to the other catalysts in terms of better conversion and DME selectivity because of facile reducibility of the metal component, suitable topology, proper acidic property and resistance towards catalyst deactivation. (author)

  10. The first bis-cyanoxime: synthesis and properties of a new versatile and accessible polydentate bifunctional building block for coordination and supramolecular chemistry.

    Science.gov (United States)

    Cheadle, Carl; Gerasimchuk, Nikolay; Barnes, Charles L; Tyukhtenko, Sergiy I; Silchenko, Svitlana

    2013-04-14

    A new multidentate bifunctional organic ligand – di-N,N′-(2-cyano-2-oximinoacetyl)piperazine – was synthesized in high yield using a two-step procedure carried out under ambient conditions. At first, the reaction of piperazine and neat methylcyanoacetate led to the di-N,N′-(cyanoacetyl)piperazine (1), which then was converted into bis-cyanoxime, di-N,N′-(2-cyano-2-oximinoacetyl)piperazine (HL, 2) using a room temperature nitrosation reaction with gaseous methylnitrite. Synthesized bis-cyanoxime was characterized by 1H, 13C NMR, UV-visible, IR spectroscopy and the X-ray analysis. The ligand 2 exists as a mixture of three diastereomers arising from the syn- and anti-geometry of the cyanoxime group. The prolonged crystallization of 2 from an ethanol–water mixture leads to the formation of: (a) colorless crystals that according to the X-ray analysis contain a 51.2:48.8% co-crystallized mixture of both isomers that have the same H-bonding motif (minority), and (b) a white amorphous material that represents an almost pure anti-isomer (majority). The deprotonation of 2 leads to the formation of a yellow dianion that demonstrated pronounced solvatochromism of its n → π* transition in the nitroso-chromophore. The disodium salt Na2L·4H2O (3) was obtained from 2 using NaOC2H5 in ethanol. The new bis-cyanoxime 2 reacts with Tl2CO3 and AgNO3 in aqueous solutions with the formation of light-stable, sparingly soluble yellow precipitates of M′2L·xH2O composition (M′ = Tl, Ag; Tl = 4, x = 0; Ag = 5, x = 2). The reaction of 3 with Ni2+ or K2M′′Cl4 (M′′ = Pd, Pt) in aqueous solutions leads to NiL·4H2O (6), PdL·4H2O (7) and PtL·5H2O (8). The crystal structure of 4 was determined and revealed the formation of a 3D-coordination polymeric complex in which the bis-cyanoxime acts as a dianionic, bridging, formally decadentate ligand. Each Tl(I) center has two bonds (2.655, 2.769 Å), shorter than the sum of ionic radii Tl–O (oxime group), and three longer

  11. Evaluation of the different supported bifunctional electrocatalysts for unified regenerative cells; Evaluacion de diferentes soportes de electrocatalizadores bifuncionales para celdas regenerativas unificadas

    Energy Technology Data Exchange (ETDEWEB)

    Gurrola, M. P.; Torres-Amaya, D. S.; Duron-Torres, S. M.; Escalante-Garcia, I. L. [Universidad Autonoma de Zacatecas, Unidad Academica de Ciencias Quimicas, Zacatecas (Mexico)]. E-mail: duronsm@prodigy.net.mx; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo, Queretaro (Mexico)

    2009-09-15

    Unified regenerative fuel cells (URFC) represent an alternative to normal regenerative cells, providing decreased costs and space in one single device. The challenges of these systems are even greater than those for conventional fuel cells, with the most pressing technical problem being the optimization of the oxygen electrode. The high operating potentials of these devices in the electrolyzer mode, E >1.6 V vs. ENH, limit the use of supported Pt/Vulcan electrodes. The electroactivity of Pt is not sufficient to catalyze the oxygen evolution reaction (OER) and at these potentials carbon-based supports undergo corrosion. In addition to studies of materials that function as bifunctional catalysts, a significant amount of research is being aimed at the search of new matrixes for use in supporting electrocatalysts for OER and ORR{sup 1,2}. This work presents the preliminary results of the kinetic study of oxygen reactions on different Pt combinations, with IrO{sub 2} and RuO{sub 2} supported by different forms of carbon and substoichiometric titanium oxide. The studies were conducted using cyclical (CV) and linear (LV) voltamperometry for OER and rotary disc electrode (RDE) for the ORR in watery H{sub 2}SO{sub 4} 0.5M solutions. The chronoamperometry (CA) technique provided information about the electrochemical stability of the electrodes. The results indicate that the performance of the electrodes supported by different forms of carbon decreases gradually as a result of corrosion when consecutive cycles of oxygen reduction and formation reactions occur. Titanium oxide provides the greatest stability to electrodes constructed on that material and thus can potentially support oxygen electrodes based on combinations of Pt, IrO{sub 2} and RuO{sub 2} as binfunctional electrocatalysts for the URFC. [Spanish] Las celdas de combustible regenerativas unificadas (URFC) representan una alternativa a las celdas regenerativas normales que implica disminucion de costos y espacio en

  12. TiO2@Pt@CeO2 nanocomposite as a bifunctional catalyst for enhancing photo-reduction of Cr (VI) and photo-oxidation of benzyl alcohol.

    Science.gov (United States)

    Li, Shunxing; Cai, Jiabai; Wu, Xueqing; Liu, Biwen; Chen, Qiaoying; Li, Yuehai; Zheng, Fengying

    2018-03-15

    An solar-light-driven and bifunctional photocatalyst was designed for photo-reduction of Cr(VI) and selective photo-oxidation of benzyl alcohol into benzaldehyde in the presence of water under ambient conditions. Double-shelled and sandwiched TiO2@Pt@CeO2 hollow spheres were prepared by using functionalized polystyrene spheres, sol-gel, hydrothermal reaction, and calcination. The Pt nanoparticles (NPs) were controllably loaded between the TiO2 shell and CeO2 shell. Under solar-light irradiation, the photo-reduction rate of Cr(VI) (μmol h-1) was in the order of TiO2@Pt@CeO2 (1.901) > TiO2@CeO2 (1.424) > TiO2 (1.040) > CeO2 (0.992). Among the above-mentioned photocatalysts, the conversion rate of benzyl alcohol for TiO2@Pt@CeO2 was also the best. These results were attributed to the combination of TiO2 and CeO2 as photocatalyst and oxygen buffer, the double-shelled and sandwiched nanostructure, and the addition of Pt NPs as cocatalyst and electron trap site, which could store and shuttle photo-generated electrons, reduce the recombination of the electron-hole, and then enhance photo-generation of active radicals. This conclusion was verified by the electron paramagnetic resonance (EPR) spectroscopy. Considering the versatile combination of photocatalyst, oxygen buffer and cocatalyst, this work could provide new insights into the design of high-performance bifunctional photocatalysts for heavy metal removal and selective synthesis. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. p-NO2-Bn-H4neunpa and H4neunpa-Trastuzumab: Bifunctional Chelator for Radiometalpharmaceuticals and (111)In Immuno-Single Photon Emission Computed Tomography Imaging.

    Science.gov (United States)

    Spreckelmeyer, Sarah; Ramogida, Caterina F; Rousseau, Julie; Arane, Karen; Bratanovic, Ivica; Colpo, Nadine; Jermilova, Una; Dias, Gemma M; Dude, Iulia; Jaraquemada-Peláez, Maria de Guadalupe; Bénard, François; Schaffer, Paul; Orvig, Chris

    2017-08-16

    Potentially nonadentate (N5O4) bifunctional chelator p-SCN-Bn-H4neunpa and its immunoconjugate H4neunpa-trastuzumab for (111)In radiolabeling are synthesized. The ability of p-SCN-Bn-H4neunpa and H4neunpa-trastuzumab to quantitatively radiolabel (111)InCl3 at an ambient temperature within 15 or 30 min, respectively, is presented. Thermodynamic stability determination with In(3+), Bi(3+), and La(3+) resulted in high conditional stability constant (pM) values. In vitro human serum stability assays have demonstrated both (111)In complexes to have high stability over 5 days. Mouse biodistribution of [(111)In][In(p-NO2-Bn-neunpa)](-), compared to that of [(111)In][In(p-NH2-Bn-CHX-A″-diethylenetriamine pentaacetic acid (DTPA))](2-), at 1, 4, and 24 h shows fast clearance of both complexes from the mice within 24 h. In a second mouse biodistribution study, the immunoconjugates (111)In-neunpa-trastuzumab and (111)In-CHX-A″-DTPA-trastuzumab demonstrate a similar distribution profile but with slightly lower tumor uptake of (111)In-neunpa-trastuzumab compared to that of (111)In-CHX-A″-DTPA-trastuzumab. These results were also confirmed by immuno-single photon emission computed tomography (immuno-SPECT) imaging in vivo. These initial investigations reveal the acyclic bifunctional chelator p-SCN-Bn-H4neunpa to be a promising chelator for (111)In (and other radiometals) with high in vitro stability and also show H4neunpa-trastuzumab to be an excellent (111)In chelator with promising biodistribution in mice.

  14. An electrochemical biosensor for rapid detection of E. coli O157:H7 with highly efficient bi-functional glucose oxidase-polydopamine nanocomposites and Prussian blue modified screen-printed interdigitated electrodes.

    Science.gov (United States)

    Xu, Meng; Wang, Ronghui; Li, Yanbin

    2016-09-21

    The presence of pathogenic bacteria in foods has always been a great threat to the wellbeing of people and the revenue of food manufacturers. Therefore, the demand for advanced detection methods that can sensitively and rapidly detect these pathogens has been of great importance. This study reports an electrochemical biosensor for rapid detection of E. coli O157:H7 with the integration of bifunctional glucose oxidase (GOx)-polydopamine (PDA) based polymeric nanocomposites (PMNCs) and Prussian blue (PB) modified screen-printed interdigitated microelectrodes (SP-IDMEs). The core-shell magnetic beads (MBs)-GOx@PDA PMNCs were first synthesized by the self-polymerization of dopamine (DA). Gold nanoparticles (AuNPs) were dispersed on the surface of PMNCs through biochemical synthesis to achieve further highly efficient adsorption of antibodies (ABs) and GOx. The final product ABs/GOxext/AuNPs/MBs-GOx@PDA PMNCs served as the carrier to separate target bacteria from food matrices as well as the amplifier for electrochemical measurement. The unbound PMNCs were separated by a filtration step and transferred into glucose solution to allow the enzymatic reaction to occur. The change of the current response was measured with an electrochemical detector using PB-modified SP-IDMEs. The constructed biosensor has been proven to be able to detect E. coli O157:H7 with the detection limit of 10(2) cfu ml(-1). The bifunctional PMNCs contain a high load of enzyme and can optimally utilize the binding sites on bacterial cells, which efficiently amplify the signals for measurement. The biosensor in this study exhibited good specificity, reproducibility, and stability and is expected to have a great impact on applications in the detection of foodborne pathogens.

  15. Evidence that DNA helicase I and oriT site-specific nicking are both functions of the F TraI protein.

    Science.gov (United States)

    Traxler, B A; Minkley, E G

    1988-11-05

    Site-specific and strand-specific nicking at the origin of transfer (oriT) of the F sex factor is the initial step in conjugal DNA metabolism. Then, DNA helicase I, the product of the traI gene, processively unwinds the plasmid from the nick site to generate the single strand of DNA that is transferred to the recipient. The nick at oriT is produced by the combined action of two Tra proteins, TraY and TraZ. The traZ gene was never precisely mapped, as no available point mutation uniquely affected TraZ-dependent oriT nicking. With several new mutations, we have demonstrated that TraZ activity is dependent upon traI DNA sequences. The simplest interpretation of this finding is that the F TraI protein is bifunctional, with DNA unwinding and site-specific DNA nicking activities.

  16. Whey Protein

    Science.gov (United States)

    ... protein daily for 2 years does not improve bone density in postmenopausal women with osteoporosis. Weight loss. Most research suggests that taking whey protein alone, along with diet modifications, or while following an exercise plan does not seem to reduce weight for ...

  17. Protein Extractability

    African Journals Online (AJOL)

    limited to high oleic acid oil and water purification property (Katayon et al., 2006; Foid et al., 2001 and. Folkard et al., 1993), whereas it contains up to. 332.5 g of crude protein per kg of sample (Jose et al., 1999). Studies to characterize the interaction effects of pH and salts on the extraction of. PROTEIN EXTRACTABILITY ...

  18. Tau protein

    DEFF Research Database (Denmark)

    Frederiksen, Jette Lautrup Battistini; Kristensen, Kim; Bahl, Jmc

    2011-01-01

    Background: Tau protein has been proposed as biomarker of axonal damage leading to irreversible neurological impairment in MS. CSF concentrations may be useful when determining risk of progression from ON to MS. Objective: To investigate the association between tau protein concentration and 14......-3-3 protein in the cerebrospinal fluid (CSF) of patients with monosymptomatic optic neuritis (ON) versus patients with monosymptomatic onset who progressed to multiple sclerosis (MS). To evaluate results against data found in a complete literature review. Methods: A total of 66 patients with MS and/or ON from...... the Department of Neurology of Glostrup Hospital, University of Copenhagen, Denmark, were included. CSF samples were analysed for tau protein and 14-3-3 protein, and clinical and paraclinical information was obtained from medical records. Results: The study shows a significantly increased concentration of tau...

  19. Lipochitin oligosaccharides immobilized through oximes in glycan microarrays bind LysM proteins.

    Science.gov (United States)

    Maolanon, Nicolai N; Blaise, Mickael; Sørensen, Kasper K; Thygesen, Mikkel B; Cló, Emiliano; Sullivan, John T; Ronson, Clive W; Stougaard, Jens; Blixt, Ola; Jensen, Knud J

    2014-02-10

    Glycan microarrays have emerged as novel tools to study carbohydrate-protein interactions. Here we describe the preparation of a covalent microarray with lipochitin oligosaccharides and its use in studying proteins containing LysM domains. The glycan microarray was assembled from glycoconjugates that were synthesized by using recently developed bifunctional chemoselective aminooxy reagents without the need for transient carbohydrate protecting groups. We describe for the first time the preparation of a covalent microarray with lipochitin oligosaccharides and its use for studying proteins containing LysM domains. Lipochitin oligosaccharides (also referred to as Nod factors) were isolated from bacterial strains or chemoenzymatically synthesized. The glycan microarray also included peptidoglycan-related compounds, as well as chitin oligosaccharides of different lengths. In total, 30 ligands were treated with the aminooxy linker molecule. The identity of the glycoconjugates was verified by mass spectrometry, and they were then immobilized on the array. The presence of the glycoconjugates on the array surface was confirmed by use of lectins and human sera (IgG binding). The functionality of our array was tested with a bacterial LysM domain-containing protein, autolysin p60, which is known to act on the bacterial cell wall peptidoglycan. P60 showed specific binding to Nod factors and to chitin oligosaccharides. Increasing affinity was observed with increasing chitin oligomer length. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A novel peptidoglycan binding protein crucial for PBP1A-mediated cell wall biogenesis in Vibrio cholerae.

    Directory of Open Access Journals (Sweden)

    Tobias Dörr

    2014-06-01

    Full Text Available The bacterial cell wall, which is comprised of a mesh of polysaccharide strands crosslinked via peptide bridges (peptidoglycan, PG, is critical for maintenance of cell shape and survival. PG assembly is mediated by a variety of Penicillin Binding Proteins (PBP whose fundamental activities have been characterized in great detail; however, there is limited knowledge of the factors that modulate their activities in different environments or growth phases. In Vibrio cholerae, the cause of cholera, PG synthesis during the transition into stationary phase is primarily mediated by the bifunctional enzyme PBP1A. Here, we screened an ordered V. cholerae transposon library for mutants that are sensitive to growth inhibition by non-canonical D-amino acids (DAA, which prevent growth and maintenance of cell shape in PBP1A-deficient V. cholerae. In addition to PBP1A and its lipoprotein activator LpoA, we found that CsiV, a small periplasmic protein with no previously described function, is essential for growth in the presence of DAA. Deletion of csiV, like deletion of lpoA or the PBP1A-encoding gene mrcA, causes cells to lose their rod shape in the presence of DAA or the beta-lactam antibiotic cefsulodin, and all three mutations are synthetically lethal with deletion of mrcB, which encodes PBP1B, V. cholerae's second key bifunctional PBP. CsiV interacts with LpoA and PG but apparently not with PBP1A, supporting the hypothesis that CsiV promotes LpoA's role as an activator of PBP1A, and thereby modulates V. cholerae PG biogenesis. Finally, the requirement for CsiV in PBP1A-mediated growth of V. cholerae can be overcome either by augmenting PG synthesis or by reducing PG degradation, thereby highlighting the importance of balancing these two processes for bacterial survival.

  1. Protein-Protein Interaction Databases

    DEFF Research Database (Denmark)

    Szklarczyk, Damian; Jensen, Lars Juhl

    2015-01-01

    of research are explored. Here we present an overview of the most widely used protein-protein interaction databases and the methods they employ to gather, combine, and predict interactions. We also point out the trade-off between comprehensiveness and accuracy and the main pitfall scientists have to be aware...

  2. Dietary Proteins

    Science.gov (United States)

    ... because your body doesn't store it the way it stores fats or carbohydrates. How much you need depends on your age, sex, health, and level of physical activity. Most Americans eat enough protein in their diet.

  3. Molecular Design of Bisphosphonate-Modified Proteins for Efficient Bone Targeting In Vivo.

    Directory of Open Access Journals (Sweden)

    Hidemasa Katsumi

    Full Text Available To establish a rational molecular design for bisphosphonate (BP-modified proteins for efficient bone targeting, a pharmacokinetic study was performed using a series of alendronate (ALN, a nitrogen-containing BP, modified proteins with various molecular weights and varying degrees of modification. Four proteins with different molecular weight-yeast glutathione reductase (GR; MW: 112,000 Da, bovine serum albumin (BSA; MW: 67,000 Da, recombinant human superoxide dismutase (SOD; MW: 32,000 Da, and chicken egg white lysozyme (LZM; MW: 14,000 Da-were modified with ALN to obtain ALN-modified proteins. Pharmacokinetic analysis of the tissue distribution of the ALN-modified and unmodified proteins was performed after radiolabeling them with indium-111 (111In by using a bifunctional chelating agent. Calculation of tissue uptake clearances revealed that the bone uptake clearances of 111In-ALN-modified proteins were proportional to the degree of ALN modification. 111In-GR-ALN and BSA-ALN, the two high-molecular-weight proteins, efficiently accumulated in bones, regardless of the degree of ALN modification. Approximately 36 and 34% of the dose, respectively, was calculated to be delivered to the bones. In contrast, the maximum amounts taken up by bone were 18 and 13% of the dose for 111In-SOD-ALN(32 and LZM-ALN(9, respectively, because of their high renal clearance. 111In-SOD modified with both polyethylene glycol (PEG and ALN (111In-PEG-SOD-ALN was efficiently delivered to the bone. Approximately 36% of the dose was estimated to be delivered to the bones. In an experimental bone metastasis mouse model, treatment with PEG-SOD-ALN significantly reduced the number of tumor cells in the bone of the mice. These results indicate that the combination of PEG and ALN modification is a promising approach for efficient bone targeting of proteins with a high total-body clearance.

  4. The fate of a designed protein corona on nanoparticles in vitro and in vivo.

    Science.gov (United States)

    Bargheer, Denise; Nielsen, Julius; Gébel, Gabriella; Heine, Markus; Salmen, Sunhild C; Stauber, Roland; Weller, Horst; Heeren, Joerg; Nielsen, Peter

    2015-01-01

    A variety of monodisperse superparamagnetic iron oxide particles (SPIOs) was designed in which the surface was modified by PEGylation with mono- or bifunctional poly(ethylene oxide)amines (PEG). Using (125)I-labeled test proteins (transferrin, albumin), the binding and exchange of corona proteins was studied first in vitro. Incubation with (125)I-transferrin showed that with increasing grade of PEGylation the binding was substantially diminished without a difference between simply adsorbed and covalently bound protein. However, after incubation with excess albumin and subsequently whole plasma, transferrin from the preformed transferrin corona was more and more lost from SPIOs in the case of adsorbed proteins. If non-labeled transferrin was used as preformed corona and excess (125)I-labeled albumin was added to the reaction mixtures with different SPIOs, a substantial amount of label was bound to the particles with initially adsorbed transferrin but little or even zero with covalently bound transferrin. These in vitro experiments show a clear difference in the stability of a preformed hard corona with adsorbed or covalently bound protein. This difference seems, however, to be of minor importance in vivo when polymer-coated (59)Fe-SPIOs with adsorbed or covalently bound (125)I-labeled mouse transferrin were injected intravenously in mice. With both protein coronae the (59)Fe/(125)I-labelled particles were cleared from the blood stream within 30 min and appeared in the liver and spleen to a large extent (>90%). In addition, after 2 h already half of the (125)I-labeled transferrin from both nanodevices was recycled back into the plasma and into tissue. This study confirms that adsorbed transferrin from a preformed protein corona is efficiently taken up by cells. It is also highlighted that a radiolabelling technique described in this study may be of value to investigate the role of protein corona formation in vivo for the respective nanoparticle uptake.

  5. The fate of a designed protein corona on nanoparticles in vitro and in vivo

    Directory of Open Access Journals (Sweden)

    Denise Bargheer

    2015-01-01

    Full Text Available A variety of monodisperse superparamagnetic iron oxide particles (SPIOs was designed in which the surface was modified by PEGylation with mono- or bifunctional poly(ethylene oxideamines (PEG. Using 125I-labeled test proteins (transferrin, albumin, the binding and exchange of corona proteins was studied first in vitro. Incubation with 125I-transferrin showed that with increasing grade of PEGylation the binding was substantially diminished without a difference between simply adsorbed and covalently bound protein. However, after incubation with excess albumin and subsequently whole plasma, transferrin from the preformed transferrin corona was more and more lost from SPIOs in the case of adsorbed proteins. If non-labeled transferrin was used as preformed corona and excess 125I-labeled albumin was added to the reaction mixtures with different SPIOs, a substantial amount of label was bound to the particles with initially adsorbed transferrin but little or even zero with covalently bound transferrin. These in vitro experiments show a clear difference in the stability of a preformed hard corona with adsorbed or covalently bound protein. This difference seems, however, to be of minor importance in vivo when polymer-coated 59Fe-SPIOs with adsorbed or covalently bound 125I-labeled mouse transferrin were injected intravenously in mice. With both protein coronae the 59Fe/125I-labelled particles were cleared from the blood stream within 30 min and appeared in the liver and spleen to a large extent (>90%. In addition, after 2 h already half of the 125I-labeled transferrin from both nanodevices was recycled back into the plasma and into tissue. This study confirms that adsorbed transferrin from a preformed protein corona is efficiently taken up by cells. It is also highlighted that a radiolabelling technique described in this study may be of value to investigate the role of protein corona formation in vivo for the respective nanoparticle uptake.

  6. cDNA cloning of the human peroxisomal enoyl-CoA hydratase: 3-Hydroxyacyl-CoA dehydrogenase bifunctional enzyme and localization to chromosome 3q26. 3-3q28: A free left Alu arm is inserted in the 3[prime] noncoding region

    Energy Technology Data Exchange (ETDEWEB)

    Hoefler, G.; Forstner, M.; Hulla, W.; Hiden, M.; Krisper, P.; Kenner, L.; Zechner, R. (Univ. of Graz (Austria)); McGuinness, M.C. (Johns Hopkins School of Medicine, Baltimore, MD (United States)); Ried, T.; Lengauer, C. (Univ. of Heidelberg (Germany)) (and others)

    1994-01-01

    Enoyl-CoA hydratase:3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme is one of the four enzymes of the peroxisomal, [beta]-oxidation pathway. Here, the authors report the full-length human cDNA sequence and the localization of the corresponding gene on chromosome 3q26.3-3q28. The cDNA sequence spans 3779 nucleotides with an open reading frame of 2169 nucleotides. The tripeptide SKL at the carboxy terminus, known to serve as a peroxisomal targeting signal, is present. DNA sequence comparison of the coding region showed an 80% homology between human and rat bifunctional enzyme cDNA. The 3[prime] noncoding sequence contains 117 nucleotides homologous to an Alu repeat. Based on sequence comparison, they propose that these nucleotides are a free left Alu arm with 86% homology to the Alu-J family. RNA analysis shows one band with highest intensity in liver and kidney. This cDNA will allow in-depth studies of molecular defects in patients with defective peroxisomal bifunctional enzyme. Moreover, it will also provide a means for studying the regulation of peroxisomal [beta]-oxidation in humans. 33 refs., 5 figs.

  7. Identification of novel NPRAP/δ-catenin-interacting proteins and the direct association of NPRAP with dynamin 2.

    Directory of Open Access Journals (Sweden)

    Carolina Koutras

    Full Text Available Neural plakophilin-related armadillo protein (NPRAP or δ-catenin is a neuronal-specific protein that is best known for its interaction with presenilin 1 (PS1. Interestingly, the hemizygous loss of NPRAP is associated with severe mental retardation in cri du chat syndrome (CDCS, and mutations in PS1 cause an aggressive, early-onset form of Alzheimer's disease. Until recently, studies on the function of NPRAP have focused on its ability to modulate dendritic protrusion elaboration through its binding to cell adhesion and scaffolding molecules. However, mounting evidence indicates that NPRAP participates in intracellular signaling and exists in the nucleus, where it modulates gene expression. This apparent bifunctional nature suggests an elaborate neuronal role, but how NPRAP came to participate in such distinct subcellular events remains a mystery. To gain insight into this pathway, we immunoprecipitated NPRAP from human SH SY5Y cells and identified several novel interacting proteins by mass spectrometry. These included neurofilament alpha-internexin, interferon regulatory protein 2 binding factors, and dynamins 1 and 2. We further validated dynamin 2/NPRAP colocalization and direct interaction in vivo, confirming their bona fide partnership. Interestingly, dynamin 2 has established roles in endocytosis and actin assembly, and both of these processes have the potential to interface with the cell adhesion and intracellular signaling processes that involve NPRAP. Our data provide new avenues for approaching NPRAP biology and suggest a broader role for this protein than previously thought.

  8. Identification of Novel NPRAP/δ-Catenin-Interacting Proteins and the Direct Association of NPRAP with Dynamin 2

    Science.gov (United States)

    Koutras, Carolina; Lévesque, Georges

    2011-01-01

    Neural plakophilin-related armadillo protein (NPRAP or δ-catenin) is a neuronal-specific protein that is best known for its interaction with presenilin 1 (PS1). Interestingly, the hemizygous loss of NPRAP is associated with severe mental retardation in cri du chat syndrome (CDCS), and mutations in PS1 cause an aggressive, early-onset form of Alzheimer's disease. Until recently, studies on the function of NPRAP have focused on its ability to modulate dendritic protrusion elaboration through its binding to cell adhesion and scaffolding molecules. However, mounting evidence indicates that NPRAP participates in intracellular signaling and exists in the nucleus, where it modulates gene expression. This apparent bifunctional nature suggests an elaborate neuronal role, but how NPRAP came to participate in such distinct subcellular events remains a mystery. To gain insight into this pathway, we immunoprecipitated NPRAP from human SH SY5Y cells and identified several novel interacting proteins by mass spectrometry. These included neurofilament alpha-internexin, interferon regulatory protein 2 binding factors, and dynamins 1 and 2. We further validated dynamin 2/NPRAP colocalization and direct interaction in vivo, confirming their bona fide partnership. Interestingly, dynamin 2 has established roles in endocytosis and actin assembly, and both of these processes have the potential to interface with the cell adhesion and intracellular signaling processes that involve NPRAP. Our data provide new avenues for approaching NPRAP biology and suggest a broader role for this protein than previously thought. PMID:22022388

  9. Bifunctional electrodes with ir and Ru oxide mixtures and pt for unified regenerative cells; Electrodos bifuncionales basados en mezclas de oxidos de Ir y Ru con Pt para celdas regenerativas unificadas

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S.M.; Escalante-Garcia, I.L. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico); Cruz, J. C.; Arriaga-Hurtado; L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo, Queretaro (Mexico)]. E-mail: duronsm@prodigy.net.mx

    2009-09-15

    Unified regenerative fuel cells (URFC) represent an attractive option to obtain hydrogen and generate energy using a compact device. Nevertheless, the fusion of a fuel cell (PEMFC) and a water electrolyzer continue to be a challenge because of the wide range of conditions to which this type of device is subject. Because of its kinetic characteristics, oxygen reduction reaction (ORR) in PEMFC and oxygen evolution reaction (OER) in PEMWE are the limiting stages of the URFC depending on the mode of operation. The primary focus of research related to URFC is the obtainment of bifunctional electrocatalysts that satisfactorily perform in both oxygen reactions and support the different working conditions found in a fuel cell and an electrolyzer. The present work contributes to the research on bifunctional electrocatalysts and shows some preliminary results from the electrochemical study of different Pt gcc, IrO{sub 2} and RuO{sub 2} mixtures supported in Ebonex® as oxygen electrodes. The electrochemical characterization with cyclic voltamperometry (CV), linear voltamperometry (LV) and electrochemical impedance spectroscopy (EIS) in H{sub 2}SO{sub 4} 0.5 M, in the absence and present of oxygen shows that Ebonex®-supported bifunctional electrodes IrO{sub 2}-Pt and RuO{sub 2}-Pt present reasonable electrocatalytic properties for oxygen evolution and reduction reactions and present the possibility of their use in an URFC. The Ir- based oxide electrodes show greater stability than ruthenium-oxide electrodes. [Spanish] Las celdas de combustible regenerativas unificadas (URFC) representan una atractiva opcion para la obtencion de hidrogeno y generacion de energia en un dispositivo compacto. Sin embargo, la fusion de una celda de combustible (PEMFC) y un electrolizador de agua (PEMWE) sigue siendo un reto por la amplia gama de condiciones a que se sujeta un dispositivo de este tipo. Por sus caracteristicas cineticas, la reaccion de reduccion de oxigeno (ORR) en la PEMFC y la

  10. Protein Crystallization

    Science.gov (United States)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  11. Synergy of adsorption and visible-light photocatalytic degradation of methylene blue by a bifunctional Z-scheme heterojunction of WO{sub 3}/g-C{sub 3}N{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xin; Jin, Ailing; Jia, Yushuai, E-mail: ysjia@jxnu.edu.cn; Xia, Tonglin; Deng, Chenxin; Zhu, Meihua; Chen, Changfeng; Chen, Xiangshu, E-mail: cxs66cn@jxnu.edu.cn

    2017-05-31

    Highlights: • We designed and fabricated a novel WO{sub 3}/g-C{sub 3}N{sub 4} bifunctional Z-scheme photocatalyst. • Synergistic effect between adsorption and photocatalytic elimination for MB. • The integrated removal efficiency is governed by WO{sub 3} content in the composite. • Adsorption kinetics and isotherm for MB over the photocatalyst were investigated. • A novel Z-scheme photocatalytic mechanism is proposed. - Abstract: A novel bifunctional Z-scheme heterojunction possessing high adsorption and photocatalytic activity, WO{sub 3}/g-C{sub 3}N{sub 4} with well-defined morphology has been successfully synthesized by in-situ liquid phase process and characterized by various analytical techniques. The degradation experiments demonstrate that the Z-scheme photocatalyst shows a synergistic effect between adsorption and photocatalysis for the removal of methylene blue (MB) under visible-light irradiation, with the optimum adsorption and photocatalytic activity both found at 30 wt% WO{sub 3}/g-C{sub 3}N{sub 4}. Under illumination, the photodegradation performance of 30 wt% WO{sub 3}/g-C{sub 3}N{sub 4} is improved to 2.5 and 2.7 times that of pure g-C{sub 3}N{sub 4} and pure WO{sub 3}, respectively. The possible mechanism for the photocatalytic activity enhancement could be attributed to the formation of a Z-scheme heterojunction system based on the active species trapping experiments. Furthermore, the investigations of adsorption kinetics and isotherm show that the adsorption process can be well described by pseudo-second-order kinetic model, and the adsorption capacity of 30 wt% WO{sub 3}/g-C{sub 3}N{sub 4} is enhanced to 4 times that of pure WO{sub 3}, with a maximum of 97.00 mg g{sup −1} determined by Langmuir isotherm. As evidenced by N{sub 2} physisorption, zeta potential and time-resolved photoluminescence measurements, the significant enhancement of the integrated adsorption and photocatalytic degradation efficiency is mainly due to the

  12. HIGLE is a bifunctional homing endonuclease that directly interacts with HYL1 and SERRATE in Arabidopsis thaliana

    DEFF Research Database (Denmark)

    Cho, Seok Keun; Ryu, Moon Young; Poulsen, Christian

    2017-01-01

    A highly coordinated complex known as the microprocessor precisely processes primary transcripts of MIRNA genes into mature miRNAs. In plants, the microprocessor minimally consists of three components: Dicer-like protein 1 (DCL1), HYPONASTIC LEAF 1 (HYL1), and SERRATE (SE). To precisely modulate mi......RNA maturation, the microprocessor cooperates with at least 12 proteins in plants. In addition, we here show the involvement of a novel gene, HYL1-interacting GIY-YIG-like endonuclease (HIGLE). The encoded protein has a GIY-YIG domain that is generally found within a class of homing endonucleases. HIGLE directly...... interacts with the microprocessor components HYL1 and SE. Unlike the functions of other GIY-YIG endonucleases, the catalytic core of HIGLE has both DNase and RNase activities that sufficiently processes miRNA precursors into short fragments in vitro....

  13. A 55,000-60,000 Mr receptor protein for urokinase-type plasminogen activator. Identification in human tumor cell lines and partial purification

    DEFF Research Database (Denmark)

    Nielsen, L S; Kellerman, G M; Behrendt, N

    1988-01-01

    The iodinated Mr approximately equal to 15,000 amino-terminal fragment (ATF) of the urokinase-type plasminogen activator (u-PA) molecule bound specifically to the cell surface of all of seven cultured human tumor cell lines studied. Cross-linking of iodinated ATF to the cell surface using...... a bifunctional amino-reactive reagent followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography revealed with the four cell lines studied the occurrence of a single band migrating with an Mr of 70,000-75,000, indicating complex formation with an Mr of 55,000-60,000 u-PA receptor...... protein (u-PA-R). In the human monocyte cell line U937 cultivated in the presence of phorbol ester, the amount of complex was strongly increased, and a fraction of the complex had a slower electrophoretic mobility. Comparison between autoradiograms of reduced and unreduced samples suggests that u...

  14. Role of Key Residues at the Flavin Mononucleotide (FMN:Adenylyltransferase Catalytic Site of the Bifunctional Riboflavin Kinase/Flavin Adenine Dinucleotide (FAD  Synthetase from Corynebacterium ammoniagenes

    Directory of Open Access Journals (Sweden)

    Susana Frago

    2012-11-01

    Full Text Available In mammals and in yeast the conversion of Riboflavin (RF into flavin mononucleotide (FMN and flavin adenine dinucleotide (FAD is catalysed by the sequential action of two enzymes: an ATP:riboflavin kinase (RFK and an ATP:FMN adenylyltransferase (FMNAT. However, most prokaryotes depend on a single bifunctional enzyme, FAD synthetase (FADS, which folds into two modules: the C-terminal associated with RFK activity and the N-terminal associated with FMNAT activity. Sequence and structural analysis suggest that the 28-HxGH-31, 123-Gx(D/N-125 and 161-xxSSTxxR-168 motifs from FADS must be involved in ATP stabilisation for the adenylylation of FMN, as well as in FAD stabilisation for FAD phyrophosphorolysis. Mutants were produced at these motifs in the Corynebacterium ammoniagenes FADS (CaFADS. Their effects on the kinetic parameters of CaFADS activities (RFK, FMNAT and FAD pyrophosphorilase, and on substrates and product binding properties indicate that H28, H31, N125 and S164 contribute to the geometry of the catalytically competent complexes at the FMNAT-module of CaFADS.

  15. Facile formation of 2D Co2P@Co3O4 microsheets through in-situ toptactic conversion and surface corrosion: Bifunctional electrocatalysts towards overall water splitting

    Science.gov (United States)

    Yao, Lihua; Zhang, Nan; Wang, Yin; Ni, Yuanman; Yan, Dongpeng; Hu, Changwen

    2018-01-01

    Exploring efficient non-precious electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial for many renewable energy conversion processes. In this work, we report that 2D Co2P@Co3O4 microsheets can be prepared through an in-situ toptactic conversion from single-crystal β-Co(OH)2 microplatelets, associated with a surface phosphatization and corrosion process. The resultant Co2P@Co3O4 2D hybrid materials can further serve as self-supported bifunctional catalytic electrodes to drive the overall water splitting for HER and OER simultaneously, with low overpotentials and high long-term stability. Furthermore, a water electrolyzer based on Co2P@Co3O4 hybrid as both anode and cathode is fabricated, which achieves 10 mA cm-2 current at only 1.57 V during water splitting process. Therefore, this work provides a facile strategy to obtain 2D Co2P-based micro/nanostructures, which act as low-cost and highly active electrocatalysts towards overall water splitting application.

  16. Electrosynthesis of an imidazole derivative and its application as a bifunctional electrocatalyst for simultaneous determination of ascorbic acid, adrenaline, acetaminophen, and tryptophan at a multi-wall carbon nanotubes modified electrode surface.

    Science.gov (United States)

    Nasirizadeh, Navid; Shekari, Zahra; Zare, Hamid R; Shishehbore, M Reza; Fakhari, Ali R; Ahmar, Hamid

    2013-03-15

    In this research, the electrosynthesis of 4-(1H-benzo[d]imidazol-2-ylthio)-5-methylbenze-1,2-diol (as an imidazole derivative) is reported. An imidazole derivative multi-wall carbon nanotube modified glassy carbon electrode (IMWCNT-GCE) was constructed and used as an excellent bifunctional electrocatalyst for oxidation of ascorbic acid (AA) and adrenaline (AD). Cyclic voltammetry was used to calculate the surface electron transfer rate constant, k(s), and the electron transfer coefficient, α, for the electron transfer between MWCNT-GCE and the electrodeposited imidazole derivative. The kinetic parameters such as the electron transfer coefficient, α, and the heterogeneous rate constant, k', for the oxidation of AA and AD at the IMWCNT-GCE surface were estimated. The modified electrode was found quite effective for the simultaneous determination of AA, AD, acetaminophen (AC), and tryptophan (Trp) in a mixture solution. The detection limits of AA and AD were calculated as 0.96 μM and 0.38 μM, respectively. Finally, IMWCNT-GCE was satisfactorily used for the determination of AA, AD, and AC in pharmaceutical samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Fe3 N-Co2 N Nanowires Array: A Non-Noble-Metal Bifunctional Catalyst Electrode for High-Performance Glucose Oxidation and H2 O2 Reduction toward Non-Enzymatic Sensing Applications.

    Science.gov (United States)

    Zhou, Dan; Cao, Xiaoqin; Wang, Zao; Hao, Shuai; Hou, Xiandeng; Qu, Fengli; Du, Gu; Asiri, Abdullah M; Zheng, Chengbin; Sun, Xuping

    2017-04-19

    Among reported electrode materials, a nanoarray is an attractive architecture for molecular detection because of its large specific surface area and easy accessibility for target molecules. Here, a new Fe3 N-Co2 N nanowires array grown on carbon cloth (Fe3 N-Co2 N/CC) is reported as a non-noble-metal bifunctional catalyst electrode for high-performance glucose oxidation and H2 O2 reduction. As an electrochemical non-enzymatic sensor for glucose detection, Fe3 N-Co2 N/CC shows a fast response time of 8 s, a low detection limit (LOD) of 77 nm (signal/noise=3), and a high sensitivity of 4333.7 μA mm-1  cm-2 . As an H2 O2 sensor, it shows a LOD of 59 nm (signal/noise=3) and a sensitivity of 2273.8 μA mm-1  cm-2 with a response time of 2 s. In addition, the proposed sensor is stable with high selectivity, specificity, and reproducibility, and its application for real sample analysis has been successfully demonstrated. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Fabrication of α-Fe{sub 2}O{sub 3}/TiO{sub 2} bi-functional composites with hierarchical and hollow structures and their application in water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yinhui, E-mail: lillian09281@hotmail.com; Zhang, Na; Chen, Jianxin, E-mail: chjx2000@126.com; Li, Ruijuan; Li, Liang; Li, Kunyu [Hebei University of Technology, School of Marine Science and Engineering, Engineering Research Center of Seawater Utilization Technology, Ministry of Education (China)

    2016-02-15

    The α-Fe{sub 2}O{sub 3}/TiO{sub 2} bi-functional composites with hierarchical and hollow structures are fabricated through a hydrothermal route. The adsorption performance and photocatalytic activity of the composites towards Pb{sup 2+} are investigated in this work. Different adsorption kinetics models and equilibrium models are used to explore the adsorption behavior of hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres. Experimental data show that adsorption kinetics of the hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres can be fitted well by the pseudo-second-order model, while the isothermal data can be perfectly described by the Langmuir adsorption model. The maximum adsorption capacity of the hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres is 32.36 mg g{sup −1}. Moreover, the hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres possess photocatalytic oxidation character under simulated solar light irradiation. The results demonstrate that the hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres, as effective and cheap materials, can be applied to the removal of heavy metal ions from wastewater.

  19. Crab-shell induced synthesis of ordered macroporous carbon nanofiber arrays coupled with MnCo2O4 nanoparticles as bifunctional oxygen catalysts for rechargeable Zn-air batteries.

    Science.gov (United States)

    Bin, Duan; Guo, Ziyang; Tamirat, Andebet Gedamu; Ma, Yuanyuan; Wang, Yonggang; Xia, Yongyao

    2017-08-10

    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out using noble metals (such as Pt) and metal oxides (such as RuO2 and IrO2) as catalysts, respectively. Nevertheless, several key issues such as high cost, poor stability, and detrimental environmental effects limit the catalytic activity of these noble metal- and metal oxide-based catalysts. Herein, we have designed and synthesized macroporous carbon nanofiber arrays by using a natural crab shell template. Subsequently, spinel MnCo2O4 nanoparticles were embedded into the nitrogen-doped macroporous carbon nanofiber arrays (NMCNAs) by a hydrothermal method. Accompanied by the good conductivity, large surface area and doping of nitrogen, the as-prepared MnCo2O4/NMCNA exhibited remarkable catalytic performance and outstanding stability for both ORR and OER in alkaline media. The macroporous superstructures play vital role in reducing the ion transport resistance and facilitating the diffusion of gaseous products (O2). Finally, rechargeable Zn-air batteries using the MnCo2O4/NMCNA catalyst displayed appreciably lower overpotentials, higher power density and better stability than commercial Pt/C, thus raising the prospect of functional low-cost, non-precious-metal bifunctional catalysts in metal-air batteries.

  20. Self-assembly formation of Bi-functional Co3O4/MnO2-CNTs hybrid catalysts for achieving both high energy/power density and cyclic ability of rechargeable zinc-air battery

    Science.gov (United States)

    Xu, Nengneng; Liu, Yuyu; Zhang, Xia; Li, Xuemei; Li, Aijun; Qiao, Jinli; Zhang, Jiujun

    2016-09-01

    α-MnO2 nanotubes-supported Co3O4 (Co3O4/MnO2) and its carbon nanotubes (CNTs)-hybrids (Co3O4/MnO2-CNTs) have been successfully developed through a facile two-pot precipitation reaction and hydrothermal process, which exhibit the superior bi-functional catalytic activity for both ORR and OER. The high performance is believed to be induced by the hybrid effect among MnO2 nanotubes, hollow Co3O4 and CNTs, which can produce a synergetic enhancement. When integrated into the practical primary and electrochemically rechargeable Zn-air batteries, such a hybrid catalyst can give a discharge peak power density as high as 450 mW cm-2. At 1.0 V of cell voltage, a current density of 324 mA cm-2 is achieved. This performance is superior to all reported non-precious metal catalysts in literature for zinc-air batteries and significantly outperforms the state-of-the-art platinum-based catalyst. Particularly, the rechargeable Zn-air battery can be fabricated into all-solid-state one through a simple solid-state approach, which exhibits an excellent peak power density of 62 mW cm-2, and the charge and discharge potentials remain virtually unchanged during the overall cycles, which is comparable to the one with liquid electrolyte.

  1. In vivo functional and molecular characterization of the Penicillin-Binding Protein 4 (DacB) of Pseudomonas aeruginosa.

    Science.gov (United States)

    Aguilera Rossi, Cristian Gustavo; Gómez-Puertas, Paulino; Ayala Serrano, Juan Alfonso

    2016-10-06

    Community and nosocomial infections by Pseudomonas aeruginosa still create a major therapeutic challenge. The resistance of this opportunist pathogen to β-lactam antibiotics is determined mainly by production of the inactivating enzyme AmpC, a class C cephalosporinase with a regulation system more complex than those found in members of the Enterobacteriaceae family. This regulatory system also participates directly in peptidoglycan turnover and recycling. One of the regulatory mechanisms for AmpC expression, recently identified in clinical isolates, is the inactivation of LMM-PBP4 (Low-Molecular-Mass Penicillin-Binding Protein 4), a protein whose catalytic activity on natural substrates has remained uncharacterized until now. We carried out in vivo activity trials for LMM-PBP4 of Pseudomonas aeruginosa on macromolecular peptidoglycan of Escherichia coli and Pseudomonas aeruginosa. The results showed a decrease in the relative quantity of dimeric, trimeric and anhydrous units, and a smaller reduction in monomer disaccharide pentapeptide (M5) levels, validating the occurrence of D,D-carboxypeptidase and D,D-endopeptidase activities. Under conditions of induction for this protein and cefoxitin treatment, the reduction in M5 is not fully efficient, implying that LMM-PBP4 of Pseudomonas aeruginosa presents better behaviour as a D,D-endopeptidase. Kinetic evaluation of the direct D,D-peptidase activity of this protein on natural muropeptides M5 and D45 confirmed this bifunctionality and the greater affinity of LMM-PBP4 for its dimeric substrate. A three-dimensional model for the monomeric unit of LMM-PBP4 provided structural information which supports its catalytic performance. LMM-PBP4 of Pseudomonas aeruginosa is a bifunctional enzyme presenting both D,D-carboxypeptidase and D,D-endopeptidase activities; the D,D-endopeptidase function is predominant. Our study provides unprecedented functional and structural information which supports the proposal of this protein as a

  2. Engineering specific chemical modification sites into a collagen-like protein from Streptococcus pyogenes.

    Science.gov (United States)

    Stoichevska, Violet; Peng, Yong Y; Vashi, Aditya V; Werkmeister, Jerome A; Dumsday, Geoff J; Ramshaw, John A M

    2017-03-01

    Recombinant bacterial collagens provide a new opportunity for safe biomedical materials. They are readily expressed in Escherichia coli in good yield and can be readily purified by simple approaches. However, recombinant proteins are limited in that direct secondary modification during expression is generally not easily achieved. Thus, inclusion of unusual amino acids, cyclic peptides, sugars, lipids, and other complex functions generally needs to be achieved chemically after synthesis and extraction. In the present study, we have illustrated that bacterial collagens that have had their sequences modified to include cysteine residue(s), which are not normally present in bacterial collagen-like sequences, enable a range of specific chemical modification reactions to be produced. Various model reactions were shown to be effective for modifying the collagens. The ability to include alkyne (or azide) functions allows the extensive range of substitutions that are available via "click" chemistry to be accessed. When bifunctional reagents were used, some crosslinking occurred to give higher molecular weight polymeric proteins, but gels were not formed. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 806-813, 2017. © 2016 Wiley Periodicals, Inc.

  3. Recombinant GDNF: Tetanus toxin fragment C fusion protein produced from insect cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianhong; Chian, Ru-Ju; Ay, Ilknur; Celia, Samuel A.; Kashi, Brenda B.; Tamrazian, Eric; Matthews, Jonathan C. [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States); Remington, Mary P. [Research Service, Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201 (United States); Pepinsky, R. Blake [BiogenIdec, Inc., 14 Cambridge Center, Cambridge, MA 02142 (United States); Fishman, Paul S. [Research Service, Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201 (United States); Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201 (United States); Brown, Robert H. [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States); Francis, Jonathan W., E-mail: jwfrancisby@gmail.com [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States)

    2009-07-31

    Glial cell line-derived neurotrophic factor (GDNF) has potent survival-promoting effects on CNS motor neurons in experimental animals. Its therapeutic efficacy in humans, however, may have been limited by poor bioavailability to the brain and spinal cord. With a view toward improving delivery of GDNF to CNS motor neurons in vivo, we generated a recombinant fusion protein comprised of rat GDNF linked to the non-toxic, neuron-binding fragment of tetanus toxin. Recombinant GDNF:TTC produced from insect cells was a soluble homodimer like wild-type GDNF and was bi-functional with respect to GDNF and TTC activity. Like recombinant rat GDNF, the fusion protein increased levels of immunoreactive phosphoAkt in treated NB41A3-hGFR{alpha}-1 neuroblastoma cells. Like TTC, GDNF:TTC bound to immobilized ganglioside GT1b in vitro with high affinity and selectivity. These results support further testing of recombinant GDNF:TTC as a non-viral vector to improve delivery of GDNF to brain and spinal cord in vivo.

  4. Evolution of the magic bullet: Single chain antibody fragments for the targeted delivery of immunomodulatory proteins.

    Science.gov (United States)

    Fercher, Christian; Keshvari, Sahar; McGuckin, Michael A; Barnard, Ross T

    2018-01-01

    Immunocytokines are fusion proteins that combine the specific antigen binding capacities of an antibody or derivative thereof and the potent bioactivity of a cytokine partner. These novel biopharmaceuticals have been directed to various targets of oncological as well as non-oncological origin and a handful of promising constructs are currently advancing in the clinical trial pipeline. Several factors such as the choice of a disease specific antigen, the antibody format and the modulatory nature of the payload are crucial, not only for therapeutic efficacy and safety but also for the commercial success of such a product. In this review, we provide an overview of the basic principles and obstacles in immunocytokine design with a specific focus on single chain antibody fragment-based constructs that employ interleukins as the immunoactive component. Impact statement Selective activation of the immune system in a variety of malignancies represents an attractive approach when existing strategies have failed to provide adequate treatment options. Immunocytokines as a novel class of bifunctional protein therapeutics have emerged recently and generated promising results in preclinical and clinical studies. In order to harness their full potential, multiple different aspects have to be taken into consideration. Several key points of these fusion constructs are discussed here and should provide an outline for the development of novel products based on an overview of selected formats.

  5. Aquaporin Protein-Protein Interactions

    Directory of Open Access Journals (Sweden)

    Jennifer Virginia Roche

    2017-10-01

    Full Text Available Aquaporins are tetrameric membrane-bound channels that facilitate transport of water and other small solutes across cell membranes. In eukaryotes, they are frequently regulated by gating or trafficking, allowing for the cell to control membrane permeability in a specific manner. Protein–protein interactions play crucial roles in both regulatory processes and also mediate alternative functions such as cell adhesion. In this review, we summarize recent knowledge about aquaporin protein–protein interactions; dividing the interactions into three types: (1 interactions between aquaporin tetramers; (2 interactions between aquaporin monomers within a tetramer (hetero-tetramerization; and (3 transient interactions with regulatory proteins. We particularly focus on the structural aspects of the interactions, discussing the small differences within a conserved overall fold that allow for aquaporins to be differentially regulated in an organism-, tissue- and trigger-specific manner. A deep knowledge about these differences is needed to fully understand aquaporin function and regulation in many physiological processes, and may enable design of compounds targeting specific aquaporins for treatment of human disease.

  6. A comparison of liver protein changes in mice and hamsters treated with the peroxisome proliferator Wy-14,643.

    Energy Technology Data Exchange (ETDEWEB)

    Giometti, C. S.; Tollaksen, S. L.; Cunningham, M. L.; Center for Mechanistic Biology and Biotechnology; National Inst. of Environmental Health Sciences

    1998-01-01

    Interspecies differences in the liver response to Wy-14,643, a potent peroxisome proliferator in rats and mice, have been demonstrated. While both rats and mice show dramatic increases in the number of peroxisomes, the activity of peroxisomal enzymes involved in the {beta}-oxidation of fatty acids, and heptocyte replication, Syrian hamsters have a more moderate peroxisome proliferation response and no sustained increase in cell replication. Rats and mice, but not hamsters, develop hepatocellular carcinoma after prolonged exposure to Wy-14,643. To further characterize this species difference, two-dimensional gel electrophoresis (2-DE) has been used to compare the effect of 14-day exposure to various dietary concentrations of Wy-14,643 on liver protein expression in male mice and hamsters. Digitized images of the 2-DE protein maps were searched for significant changes. The peroxisome bifunctional enzyme (PBE) enoyl CoA hydratase/3-hydroxyacyl dehydrogenase, which migrates to the same position in mouse and hamster liver protein 2-DE patterns, increased in abundance by more than three times the control level in both mice and hamsters. In addition to the quantitative change in PBE, significant quantitative changes (P < 0.001) were found in 49 mouse liver proteins (47 decreasing and 2 increasing) and in 35 hamster liver proteins (27 decreasing and 8 increasing). There was little overlap in the mouse and hamster proteins showing quantitative changes in response to Wy-14,643, with the exception of PBE and one unidentified liver protein with an approximate molecular weight of 50 000. These results show that although peroxisome proliferation occurs in the livers of both mice and hamsters exposed to Wy-14,643, other species-specific changes in proteins occur that are independent of the peroxisome proliferation response and that could be related to species-specific susceptibility or resistance to liver tumor induction.

  7. Protein immobilization strategies for protein biochips

    NARCIS (Netherlands)

    Rusmini, F.; Rusmini, Federica; Zhong, Zhiyuan; Feijen, Jan

    2007-01-01

    In the past few years, protein biochips have emerged as promising proteomic and diagnostic tools for obtaining information about protein functions and interactions. Important technological innovations have been made. However, considerable development is still required, especially regarding protein

  8. Interaction entropy for protein-protein binding

    Science.gov (United States)

    Sun, Zhaoxi; Yan, Yu N.; Yang, Maoyou; Zhang, John Z. H.

    2017-03-01

    Protein-protein interactions are at the heart of signal transduction and are central to the function of protein machine in biology. The highly specific protein-protein binding is quantitatively characterized by the binding free energy whose accurate calculation from the first principle is a grand challenge in computational biology. In this paper, we show how the interaction entropy approach, which was recently proposed for protein-ligand binding free energy calculation, can be applied to computing the entropic contribution to the protein-protein binding free energy. Explicit theoretical derivation of the interaction entropy approach for protein-protein interaction system is given in detail from the basic definition. Extensive computational studies for a dozen realistic protein-protein interaction systems are carried out using the present approach and comparisons of the results for these protein-protein systems with those from the standard normal mode method are presented. Analysis of the present method for application in protein-protein binding as well as the limitation of the method in numerical computation is discussed. Our study and analysis of the results provided useful information for extracting correct entropic contribution in protein-protein binding from molecular dynamics simulations.

  9. Protein-mRNA interactome capture: cartography of the mRNP landscape [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Sean P. Ryder

    2016-11-01

    Full Text Available RNA-binding proteins play a variety of roles in cellular physiology. Some regulate mRNA processing, mRNA abundance, and translation efficiency. Some fight off invader RNA through small RNA-driven silencing pathways. Others sense foreign sequences in the form of double-stranded RNA and activate the innate immune response. Yet others, for example cytoplasmic aconitase, act as bi-functional proteins, processing metabolites in one conformation and regulating metabolic gene expression in another. Not all are involved in gene regulation. Some play structural roles, for example, connecting the translational machinery to the endoplasmic reticulum outer membrane. Despite their pervasive role and relative importance, it has remained difficult to identify new RNA-binding proteins in a systematic, unbiased way. A recent body of literature from several independent labs has defined robust, easily adaptable protocols for mRNA interactome discovery. In this review, I summarize the methods and review some of the intriguing findings from their application to a wide variety of biological systems.

  10. Learning about Proteins

    Science.gov (United States)

    ... Videos for Educators Search English Español Learning About Proteins KidsHealth / For Kids / Learning About Proteins What's in ... from the foods you eat. Different Kinds of Protein Protein from animal sources, such as meat and ...

  11. (S)-BINAM衍生的新型吡啶-硫脲双功能有机催化剂的合成%Synthesis of a novel(S)-BINAM-derivated pyridine-thiourea bifunctional organocatalyst

    Institute of Scientific and Technical Information of China (English)

    张辉; 朱莉莉; 张有灿

    2015-01-01

    A novel pyridine-thiourea bifunctional organocatalyst has been developed. The intermediate (Ⅱ) was synthesized by the Buchwald-Hartwig coupling reaction of(S)-2,2’-diamino-1,1’-binaphtha-lene and 2-bromopyridine under the condition of 80 ℃ with up to 60% yield. And then we used pyridine as base,trifluoroethylamine and 4-nitrophenyl chlorothionoformate in dichloromethane were stirred at room temperature for 10 min, subsequently added the intermediate (Ⅱ) and DIPEA to the reaction system, which was continued for another 12 h at room temperature,at last the catalyst(Ⅳ) can be obtained in 70% yield,and the structure was characterized by 1 H NMR,13 C NMR.%新型吡啶-硫脲双功能有机催化剂(Ⅳ),由(S)-1,1-联二萘胺(Ⅰ)和2-溴吡啶在80℃条件下经Buchwald-Hartwig偶联反应,以60%的收率得到中间体(Ⅱ);随后以吡啶为缚酸剂,三氟乙胺、硫代氯甲酸-4-硝基苯酯在二氯甲烷中于室温下反应10 min,向反应体系中加入中间体(Ⅱ)及DIPEA继续于室温下反应12 h,即可以70%的收率获得催化剂(Ⅳ)。其结构经1 H NMR和13 C NMR进行了表征。

  12. Riboflavin Accumulation and Molecular Characterization of cDNAs Encoding Bifunctional GTP Cyclohydrolase II/3,4-Dihydroxy-2-Butanone 4-Phosphate Synthase, Lumazine Synthase, and Riboflavin Synthase in Different Organs of Lycium chinense Plant

    Directory of Open Access Journals (Sweden)

    Pham Anh Tuan

    2014-10-01

    Full Text Available Riboflavin (vitamin B2 is the precursor of flavin mononucleotide and flavin adenine dinucleotide—essential cofactors for a wide variety of enzymes involving in numerous metabolic processes. In this study, a partial-length cDNA encoding bifunctional GTP cyclohydrolase II/3,4-dihydroxy-2-butanone-4-phosphate synthase (LcRIBA, 2 full-length cDNAs encoding lumazine synthase (LcLS1 and LcLS2, and a full-length cDNA encoding riboflavin synthase (LcRS were isolated from Lycium chinense, an important traditional medicinal plant. Sequence analyses showed that these genes exhibited high identities with their orthologous genes as well as having the same common features related to plant riboflavin biosynthetic genes. LcRIBA, like other plant RIBAs, contained a DHBPS region in its N terminus and a GCHII region in its C-terminal part. LcLSs and LcRS carried an N-terminal extension found in plant riboflavin biosynthetic genes unlike the orthologous microbial genes. Quantitative real-time polymerase chain reaction analysis showed that 4 riboflavin biosynthetic genes were constitutively expressed in all organs examined of L. chinense plants with the highest expression levels found in the leaves or red fruits. LcRIBA, which catalyzes 2 initial reactions in riboflavin biosynthetic pathway, was the highest transcript in the leaves, and hence, the richest content of riboflavin was detected in this organ. Our study might provide the basis for investigating the contribution of riboflavin in diverse biological activities of L. chinense and may facilitate the metabolic engineering of vitamin B2 in crop plants.

  13. In Situ Coupling of Strung Co4N and Intertwined N-C Fibers toward Free-Standing Bifunctional Cathode for Robust, Efficient, and Flexible Zn-Air Batteries.

    Science.gov (United States)

    Meng, Fanlu; Zhong, Haixia; Bao, Di; Yan, Junmin; Zhang, Xinbo

    2016-08-17

    Flexible power sources with high energy density are crucial for the realization of next-generation flexible electronics. Theoretically, rechargeable flexible zinc-air (Zn-air) batteries could provide high specific energy, while their large-scale applications are still greatly hindered by high cost and resources scarcity of noble-metal-based oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) electrocatalysts as well as inferior mechanical properties of the air cathode. Combining metallic Co4N with superior OER activity and Co-N-C with perfect ORR activity on a free-standing and flexible electrode could be a good step for flexible Zn-air batteries, while lots of difficulties need to be overcome. Herein, as a proof-of-concept experiment, we first propose a strategy for in situ coupling of strung Co4N and intertwined N-C fibers, by pyrolyzation of the novel pearl-like ZIF-67/polypyrrole nanofibers network rooted on carbon cloth. Originating from the synergistic effect of Co4N and Co-N-C and the stable 3D interconnected conductive network structure, the obtained free-standing and highly flexible bifunctional oxygen electrode exhibits excellent electrocatalytic activity and stability for both OER and ORR in terms of low overpotential (310 mV at 10 mA cm(-2)) for OER, a positive half-wave potential (0.8 V) for ORR, and a stable current density retention for at least 20 h, and especially, the obtained Zn-air batteries exhibit a low discharge-charge voltage gap (1.09 V at 50 mA cm(-2)) and long cycle life (up to 408 cycles). Furthermore, the perfect bendable and twistable and rechargeable properties of the flexible Zn-air battery particularly make it a potentially power portable and wearable electronic device.

  14. Rational Design of a Bifunctional, Two-Fold Interpenetrated ZnII-Metal-Organic Framework for Selective Adsorption of CO2and Efficient Aqueous Phase Sensing of 2,4,6-Trinitrophenol.

    Science.gov (United States)

    Singh Dhankhar, Sandeep; Sharma, Nayuesh; Kumar, Sandeep; Dhilip Kumar, T J; Nagaraja, C M

    2017-11-16

    A bifunctional, microporous Zn II metal-organic framework, [Zn 2 (NH 2 BDC) 2 (dpNDI)] n (MOF1) (where, NH 2 BDC=2-aminoterephthalic acid, dpNDI=N,N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide) has been synthesized solvothermally. MOF1 shows an interesting two-fold interpenetrated, 3D pillar-layered framework structure composed of two types of 1D channels with dimensions of approximately 2.99×3.58 Å and 4.58×5.38 Å decorated with pendent -NH 2 groups. Owing to the presence of a basic functionalized pore surface, MOF1 exhibits selective adsorption of CO 2 with high value of heat of adsorption (Q st =46.5 kJ mol -1 ) which is further supported by theoretically calculated binding energy of 48.4 kJ mol -1 . Interestingly, the value of Q st observed for MOF1 is about 10 kJ mol -1 higher than that of analogues MOF with the benzene-1,4-dicarboxylic acid (BDC) ligand, which establishes the critical role of the -NH 2 group for CO 2 capture. Moreover, MOF1 exhibits highly selective and sensitive sensing of the nitroaromatic compound (NAC), 2,4,6-trinitrophenol (TNP) over other competing NACs through a luminescence quenching mechanism. The observed selectivity for TNP over other nitrophenols has been correlated to stronger hydrogen bonding interaction of TNP with the basic -NH 2 group of MOF1, which is revealed from DFT calculations. To the best of our knowledge, MOF1 is the first example of an interpenetrated Zn II -MOF exhibiting selective adsorption of CO 2 as well as efficient aqueous-phase sensing of TNP; investigated through combined experimental and theoretical studies. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Biochemical Characterization of Bifunctional 3-Deoxy-β-d-manno-oct-2-ulosonic Acid (β-Kdo) Transferase KpsC from Escherichia coli Involved in Capsule Biosynthesis.

    Science.gov (United States)

    Ovchinnikova, Olga G; Doyle, Liam; Huang, Bo-Shun; Kimber, Matthew S; Lowary, Todd L; Whitfield, Chris

    2016-10-07

    3-Deoxy-d-manno-oct-2-ulosonic acid (Kdo) is an essential component of bacterial lipopolysaccharides, where it provides the linkage between lipid and carbohydrate moieties. In all known LPS structures, Kdo residues possess α-anomeric configurations, and the corresponding inverting α-Kdo transferases are well characterized. Recently, it has been shown that a large group of capsular polysaccharides from Gram-negative bacteria, produced by ATP-binding cassette transporter-dependent pathways, are also attached to a lipid anchor through a conserved Kdo oligosaccharide. In the study reported here, the structure of this Kdo linker was determined by NMR spectroscopy, revealing alternating β-(2→4)- and β-(2→7)-linked Kdo residues. KpsC contains two retaining β-Kdo glycosyltransferase domains belonging to family GT99 that are responsible for polymerizing the β-Kdo linker on its glycolipid acceptor. Full-length Escherichia coli KpsC was expressed and purified, together with the isolated N-terminal domain and a mutant protein (KpsC D160A) containing a catalytically inactivated N-terminal domain. The Kdo transferase activities of these proteins were determined in vitro using synthetic acceptors, and the reaction products were characterized using TLC, mass spectrometry, and NMR spectroscopy. The N- and C-terminal domains were found to catalyze formation of β-(2→4) and β-(2→7) linkages, respectively. Based on phylogenetic analyses, we propose the linkage specificities of the glycosyltransferase domains are conserved in KpsC homologs from other bacterial species. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Regulation of the activity of the dual-function DnaA protein in Caulobacter crescentus.

    Directory of Open Access Journals (Sweden)

    Carmen Fernandez-Fernandez

    Full Text Available DnaA is a conserved essential bacterial protein that acts as the initiator of chromosomal replication as well as a master transcriptional regulator in Caulobacter crescentus. Thus, the intracellular levels of active DnaA need to be tightly regulated during the cell cycle. Our previous work suggested that DnaA may be regulated at the level of its activity by the replisome-associated protein HdaA. Here, we describe the construction of a mutant DnaA protein [DnaA(R357A]. The R357 residue in the AAA+ domain of the C. crescentus DnaA protein is equivalent to the R334 residue of the E. coli DnaA protein, which is required for the Regulatory Inactivation of DnaA (RIDA. We found that the expression of the DnaA(R357A mutant protein in C. crescentus, but not the expression of the wild-type DnaA protein at similar levels, causes a severe phenotype of over-initiation of chromosomal replication and that it blocks cell division. Thus, the mutant DnaA(R357A protein is hyper-active to promote the initiation of DNA replication, compared to the wild-type DnaA protein. DnaA(R357A could not replace DnaA in vivo, indicating that the switch in DnaA activity once chromosomal replication has started may be an essential process in C. crescentus. We propose that the inactivation of DnaA is the main mechanism ensuring that chromosomal replication starts only once per cell cycle. We further observed that the R357A substitution in DnaA does not promote the activity of DnaA as a direct transcriptional activator of four important genes, encoding HdaA, the GcrA master cell cycle regulator, the FtsZ cell division protein and the MipZ spatial regulator of cell division. Thus, the AAA+ domain of DnaA may play a role in temporally regulating the bifunctionality of DnaA by reallocating DnaA molecules from initiating DNA replication to transcribing genes within the unique DnaA regulon of C. crescentus.

  17. Efficient protein alignment algorithm for protein search.

    Science.gov (United States)

    Lu, Zaixin; Zhao, Zhiyu; Fu, Bin

    2010-01-18

    Proteins show a great variety of 3D conformations, which can be used to infer their evolutionary relationship and to classify them into more general groups; therefore protein structure alignment algorithms are very helpful for protein biologists. However, an accurate alignment algorithm itself may be insufficient for effective discovering of structural relationships among tens of thousands of proteins. Due to the exponentially increasing amount of protein structural data, a fast and accurate structure alignment tool is necessary to access protein classification and protein similarity search; however, the complexity of current alignment algorithms are usually too high to make a fully alignment-based classification and search practical. We have developed an efficient protein pairwise alignment algorithm and applied it to our protein search tool, which aligns a query protein structure in the pairwise manner with all protein structures in the Protein Data Bank (PDB) to output similar protein structures. The algorithm can align hundreds of pairs of protein structures in one second. Given a protein structure, the tool efficiently discovers similar structures from tens of thousands of structures stored in the PDB always in 2 minutes in a single machine and 20 seconds in our cluster of 6 machines. The algorithm has been fully implemented and is accessible online at our webserver, which is supported by a cluster of computers. Our algorithm can work out hundreds of pairs of protein alignments in one second. Therefore, it is very suitable for protein search. Our experimental results show that it is more accurate than other well known protein search systems in finding proteins which are structurally similar at SCOP family and superfamily levels, and its speed is also competitive with those systems. In terms of the pairwise alignment performance, it is as good as some well known alignment algorithms.

  18. Structural enzymology and inhibition of the bi-functional folate pathway enzyme HPPK-DHPS from the biowarfare agent Francisella tularensis.

    Science.gov (United States)

    Shaw, Gary X; Li, Yue; Shi, Genbin; Wu, Yan; Cherry, Scott; Needle, Danielle; Zhang, Di; Tropea, Joseph E; Waugh, David S; Yan, Honggao; Ji, Xinhua

    2014-09-01

    Two valid targets for antibiotic development, 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) and dihydropteroate synthase (DHPS), catalyze consecutive reactions in folate biosynthesis. In Francisella tularensis (Ft), these two activities are contained in a single protein, FtHPPK-DHPS. Although Pemble et al. (PLoS One 5, e14165) determined the structure of FtHPPK-DHPS, they were unable to measure the kinetic parameters of the enzyme. In this study, we elucidated the binding and inhibitory activities of two HPPK inhibitors (HP-18 and HP-26) against FtHPPK-DHPS, determined the structure of FtHPPK-DHPS in complex with HP-26, and measured the kinetic parameters for the dual enzymatic activities of FtHPPK-DHPS. The biochemical analyses showed that HP-18 and HP-26 have significant isozyme selectivity, and that FtHPPK-DHPS is unique in that the catalytic efficiency of its DHPS activity is only 1/260,000 of that of Escherichia coli DHPS. Sequence and structural analyses suggest that HP-26 is an excellent lead for developing therapeutic agents for tularemia, and that the very low DHPS activity is due, at least in part, to the lack of a key residue that interacts with the substrate p-aminobenzoic acid (pABA). A BLAST search of the genomes of ten F. tularensis strains indicated that the bacterium contains a single FtHPPK-DHPS. The marginal DHPS activity and the single copy existence of FtHPPK-DHPS in F. tularensis make this bacterium more vulnerable to DHPS inhibitors. Current sulfa drugs are ineffective against tularemia; new inhibitors targeting the unique pABA-binding pocket may be effective and less subject to resistance because any mutations introducing resistance may make the marginal DHPS activity unable to support the growth of F. tularensis. The coordinates and structure factors have been deposited in the Protein Data Bank under accession code 4PZV. Published 2014. This article has been contributed to by US Government employees and their work is in

  19. Bifunctional effects of O-methylated flavones from Scutellaria baicalensis Georgi on melanocytes: Inhibition of melanin production and intracellular melanosome transport.

    Directory of Open Access Journals (Sweden)

    Michiko Kudo

    Full Text Available The growing interest in skin lightening has recently renewed attention on the esthetic applications of Chinese herbal medicine. Although Scutellaria baicalensis Georgi is used for antipyretic and antiinflammatory purposes, its whitening effect remains unclear. This study reports three major findings: (1 S. baicalensis has a potent inhibitory effect on melanogenesis; (2 wogonin and its glycoside are the active components of S. baicalensis; and (3 O-methylated flavones from S. baicalensis, such as wogonin, inhibit intracellular melanosome transport. Using a melanin quantification assay, we showed that S. baicalensis potently inhibits melanogenesis in B16F10 cells. Componential analyses revealed that the main components of S. baicalensis are baicalin, wogonoside, baicalein, wogonin, and oroxylin A. Among these five flavones, wogonin and wogonoside consistently inhibited melanogenesis in both B16F10 melanoma cells and primary melanocytes. Wogonin exhibited the strongest inhibition of melanin production and markedly lightened the color of skin equivalents. We identified microphthalmia-associated transcription factor and tyrosinase-related proteins as potential targets of wogonin- and wogonoside-induced melanogenesis suppression. In culture, we found that the melanosomes in wogonin-treated B16F10 cells were localized to the perinuclear region. Immunoblotting analyses revealed that wogonin significantly reduced in melanophilin protein, which is required for actin-based melanosome transport. Other actin-based melanosome transport-related molecules, i.e., Rab27A and myosin Va, were not affected by wogonin. Cotreatment with MG132 blocked the wogonin-induced decrease in melanophilin, suggesting that wogonin promotes the proteolytic degradation of melanophilin via the calpain/proteasomal pathway. We determined that the structural specificities of the mono-O-methyl group in the flavone A-ring and the aglycone form were responsible for reducing melanosome

  20. Small heat shock proteins, protein degradation and protein aggregation diseases

    NARCIS (Netherlands)

    Vos, Michel J.; Zijlstra, Marianne P.; Carra, Serena; Sibon, Ody C. M.; Kampinga, Harm H.

    Small heat shock proteins have been characterized in vitro as ATP-independent molecular chaperones that can prevent aggregation of un- or misfolded proteins and assist in their refolding with the help of ATP-dependent chaperone machines (e. g., the Hsp70 proteins). Comparison of the functionality of

  1. EDITORIAL: Precision proteins Precision proteins

    Science.gov (United States)

    Demming, Anna

    2010-06-01

    Since the birth of modern day medicine, during the times of Hippocrates in ancient Greece, the profession has developed from the rudimentary classification of disease into a rigorous science with an inspiring capability to treat and cure. Scientific methodology has distilled clinical diagnostic tools from the early arts of prognosis, which used to rely as much on revelation and prophecy, as intuition and judgement [1]. Over the past decade, research into the interactions between proteins and nanosystems has provided some ingenious and apt techniques for delving into the intricacies of anatomical systems. In vivo biosensing has emerged as a vibrant field of research, as much of medical diagnosis relies on the detection of substances or an imbalance in the chemicals in the body. The inherent properties of nanoscale structures, such as cantilevers, make them well suited to biosensing applications that demand the detection of molecules at very low concentrations. Measurable deflections in cantilevers functionalised with antibodies provide quantitative indicators of the presence of specific antigens when the two react. Such developments have roused mounting interest in the interactions of proteins with nanostructures, such as carbon nanotubes [3], which have demonstrated great potential as generic biomarkers. Plasmonic properties are also being exploited in sensing applications, such as the molecular sentinel recently devised by researchers in the US. The device uses the plasmonic properties of a silver nanoparticle linked to a Raman labelled hairpin DNA probe to signal changes in the probe geometry resulting from interactions with substances in the environment. Success stories so far include the detection of two specific genes associated with breast cancer [4]. A greater understanding of how RNA interference regulates gene expression has highlighted the potential of using this natural process as another agent for combating disease in personalized medicine. However, the

  2. AcEST: DK962521 [AcEST

    Lifescience Database Archive (English)

    Full Text Available nition sp|Q4KC82|ARNA_PSEF5 Bifunctional polymyxin resistance protein arnA OS=Pseudomonas fluorescens (strai...RNA_PSEF5 Bifunctional polymyxin resistance protein a... 62 2e-09 sp|Q4ZSZ2|ARNA_PSEU2 Bifunctional polymyxin... resistance protein a... 62 2e-09 sp|Q48HZ1|ARNA_PSE14 Bifunctional polymyxin resistance protein a... 62 2e...-09 sp|Q0TFI7|ARNA_ECOL5 Bifunctional polymyxin resistance protein a... 62 2e-09 sp|Q3YZV1|ARNA_SHISS Bifunctional polymyxin... resistance protein a... 62 3e-09 sp|Q83QT8|ARNA_SHIFL Bifunctional polymyxin

  3. AcEST: DK951085 [AcEST

    Lifescience Database Archive (English)

    Full Text Available 6|ARNA_AERHH Bifunctional polymyxin resistance protein arnA OS=Aeromonas hydrophila subsp. hydrophila (strai...6|ARNA_AERHH Bifunctional polymyxin resistance protein a... 174 5e-43 sp|A4SQW9|ARNA_AERS4 Bifunctional polymyxin... resistance protein a... 171 2e-42 sp|Q6D2F1|ARNA_ERWCT Bifunctional polymyxin resistance protein a... ...171 3e-42 sp|Q3YZV1|ARNA_SHISS Bifunctional polymyxin resistance protein a... 170 7e-42 sp|Q32DT3|ARNA_SHIDS Bifunctional polymyxin... resistance protein a... 170 7e-42 sp|Q31YK2|ARNA_SHIBS Bifunctional polymyxin

  4. AcEST: DK957599 [AcEST

    Lifescience Database Archive (English)

    Full Text Available C82 Definition sp|Q4KC82|ARNA_PSEF5 Bifunctional polymyxin resistance protein arnA OS=Pseudomonas fluorescen...Q4KC82|ARNA_PSEF5 Bifunctional polymyxin resistance protein a... 62 2e-09 sp|Q4ZSZ2|ARNA_PSEU2 Bifunctional polymyxin... resistance protein a... 62 3e-09 sp|Q48HZ1|ARNA_PSE14 Bifunctional polymyxin resistance protein a...... 62 3e-09 sp|Q0TFI7|ARNA_ECOL5 Bifunctional polymyxin resistance protein a... 62 3e-09 sp|Q3YZV1|ARNA_SHISS Bifunctional polymyxin... resistance protein a... 62 3e-09 sp|Q83QT8|ARNA_SHIFL Bifunctional polymyxin

  5. Co(II)1-xCo(0)x/3Mn(III)2x/3S Nanoparticles Supported on B/N-Codoped Mesoporous Nanocarbon as a Bifunctional Electrocatalyst of Oxygen Reduction/Evolution for High-Performance Zinc-Air Batteries.

    Science.gov (United States)

    Wang, Zilong; Xiao, Shuang; An, Yiming; Long, Xia; Zheng, Xiaoli; Lu, Xihong; Tong, Yexiang; Yang, Shihe

    2016-06-01

    Rechargeable Zn-air battery is an ideal type of energy storage device due to its high energy and power density, high safety, and economic viability. Its large-scale application rests upon the availability of active, durable, low-cost electrocatalysts for the oxygen reduction reaction (ORR) in the discharge process and oxygen evolution reaction (OER) in the charge process. Herein we developed a novel ORR/OER bifunctional electrocatalyst for rechargeable Zn-air batteries based on the codoping and hybridization strategies. The B/N-codoped mesoporous nanocarbon supported Co(II)1-xCo(0)x/3Mn(III)2x/3S nanoparticles exhibit a superior OER performance compared to that of IrO2 catalyst and comparable Zn-air battery performance to that of the Pt-based battery. The rechargeable Zn-air battery shows high discharge peak power density (over 250 mW cm(-2)) and current density (180 mA cm(-2) at 1 V), specific capacity (∼550 mAh g(-1)), small charge-discharge voltage gap of ∼0.72 V at 20 mA cm(-2) and even higher stability than the Pt-based battery. The advanced performance of the bifunctional catalysts highlights the beneficial role of the simultaneous formation of Mn(III) and Co(0) as well as the dispersed hybridization with the codoped nanocarbon support.

  6. Insect GDNF:TTC fusion protein improves delivery of GDNF to mouse CNS

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianhong; Chian, Ru-Ju; Ay, Ilknur; Kashi, Brenda B.; Celia, Samuel A.; Tamrazian, Eric [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States); Pepinsky, R. Blake [BiogenIdec, Inc., 14 Cambridge Center, Cambridge, MA 02142 (United States); Fishman, Paul S. [Research Service, Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201 (United States); Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201 (United States); Brown, Robert H. [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States); Francis, Jonathan W., E-mail: jwfrancisby@gmail.com [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States)

    2009-12-18

    With a view toward improving delivery of exogenous glial cell line-derived neurotrophic factor (GDNF) to CNS motor neurons in vivo, we evaluated the bioavailability and pharmacological activity of a recombinant GDNF:tetanus toxin C-fragment fusion protein in mouse CNS. Following intramuscular injection, GDNF:TTC but not recombinant GDNF (rGDNF) produced strong GDNF immunostaining within ventral horn cells of the spinal cord. Intrathecal infusion of GDNF:TTC resulted in tissue concentrations of GDNF in lumbar spinal cord that were at least 150-fold higher than those in mice treated with rGDNF. While levels of immunoreactive choline acetyltransferase and GFR{alpha}-1 in lumbar cord were not altered significantly by intrathecal infusion of rGNDF, GDNF:TTC, or TTC, only rGDNF and GDNF:TTC caused significant weight loss following intracerebroventricular infusion. These studies indicate that insect cell-derived GDNF:TTC retains its bi-functional activity in mammalian CNS in vivo and improves delivery of GDNF to spinal cord following intramuscular- or intrathecal administration.

  7. AvrRxo1 Is a Bifunctional Type III Secreted Effector and Toxin-Antitoxin System Component with Homologs in Diverse Environmental Contexts.

    Directory of Open Access Journals (Sweden)

    Lindsay R Triplett

    Full Text Available Toxin-antitoxin (TA systems are ubiquitous bacterial systems that may function in genome maintenance and metabolic stress management, but are also thought to play a role in virulence by helping pathogens survive stress. We previously demonstrated that the Xanthomonas oryzae pv. oryzicola protein AvrRxo1 is a type III-secreted virulence factor that has structural similarities to the zeta family of TA toxins, and is toxic to plants and bacteria in the absence of its predicted chaperone Arc1. In this work, we confirm that AvrRxo1 and its binding partner Arc1 function as a TA system when expressed in Escherichia coli. Sequences of avrRxo1 homologs were culled from published and newly generated phytopathogen genomes, revealing that avrRxo1:arc1 modules are rare or frequently inactivated in some species and highly conserved in others. Cloning and functional analysis of avrRxo1 from Acidovorax avenae, A. citrulli, Burkholderia andropogonis, Xanthomonas translucens, and Xanthomonas euvesicatoria showed that some AvrRxo1 homologs share the bacteriostatic and Rxo1-mediated cell death triggering activities of AvrRxo1 from X. oryzae. Additional distant putative homologs of avrRxo1 and arc1 were identified in genomic or metagenomic sequence of environmental bacteria with no known pathogenic role. One of these distant homologs was cloned from the filamentous soil bacterium Cystobacter fuscus. avrRxo1 from C. fuscus caused watersoaking and triggered Rxo1-dependent cell collapse in Nicotiana benthamiana, but no growth suppression in E. coli was observed. This work confirms that a type III effector can function as a TA system toxin, and illustrates the potential of microbiome data to reveal new environmental origins or reservoirs of pathogen virulence factors.

  8. Protein docking prediction using predicted protein-protein interface

    Directory of Open Access Journals (Sweden)

    Li Bin

    2012-01-01

    Full Text Available Abstract Background Many important cellular processes are carried out by protein complexes. To provide physical pictures of interacting proteins, many computational protein-protein prediction methods have been developed in the past. However, it is still difficult to identify the correct docking complex structure within top ranks among alternative conformations. Results We present a novel protein docking algorithm that utilizes imperfect protein-protein binding interface prediction for guiding protein docking. Since the accuracy of protein binding site prediction varies depending on cases, the challenge is to develop a method which does not deteriorate but improves docking results by using a binding site prediction which may not be 100% accurate. The algorithm, named PI-LZerD (using Predicted Interface with Local 3D Zernike descriptor-based Docking algorithm, is based on a pair wise protein docking prediction algorithm, LZerD, which we have developed earlier. PI-LZerD starts from performing docking prediction using the provided protein-protein binding interface prediction as constraints, which is followed by the second round of docking with updated docking interface information to further improve docking conformation. Benchmark results on bound and unbound cases show that PI-LZerD consistently improves the docking prediction accuracy as compared with docking without using binding site prediction or using the binding site prediction as post-filtering. Conclusion We have developed PI-LZerD, a pairwise docking algorithm, which uses imperfect protein-protein binding interface prediction to improve docking accuracy. PI-LZerD consistently showed better prediction accuracy over alternative methods in the series of benchmark experiments including docking using actual docking interface site predictions as well as unbound docking cases.

  9. Hydrothermal synthesis of superparamagnetic and red luminescent bifunctional Fe{sub 3}O{sub 4}@Mn{sup 2+}-doped NaYF{sub 4}:Yb/Er core@shell monodisperse nanoparticles and their subsequent ligand exchange in water

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Zhenli; Du, Sinan; Luo, Yang; Liao, Zhijian; Zuo, Fang, E-mail: polymerzf@swun.cn; Luo, Jianbin; Liu, Dong

    2016-08-15

    Graphical abstract: An efficient hydrothermal method was used to fabricate the superparamagnetic and red luminescent bifunctional Fe{sub 3}O{sub 4}@Mn{sup 2(*)+}-doped NaYF{sub 4}:Yb/Er nanoparticles (NPs) with core@shell structures through a seed-growth procedure. Then using PEG phosphate ligand to displace oleate from the as-synthesized NPs, hydrophilic Fe{sub 3}O{sub 4}@Mn{sup 2+}-doped NaYF{sub 4}:Yb/Er NPs with good water solubility are obtained. - Highlights: • Homogeneous size distribution of magnetic-upconversion core@shell structured nanoparticles (NPs) were synthesized. • The core@shell nanostructures were obtained by seed-growth method. • The oleic acid coated Fe{sub 3}O{sub 4} NPs were used as seeds and cores. • The magnetic-upconversion NPs emitted red luminescence under a 980 nm laser. • Synthesized magnetic-upconversion NPs were phase transferred using ligand exchange process. - Abstract: We report the use of an efficient hydrothermal method to synthesize superparamagnetic and red luminescent bifunctional Fe{sub 3}O{sub 4}@Mn{sup 2+}-doped NaYF{sub 4}:Yb/Er nanoparticles (NPs) with core@shell structures via a seed-growth procedure. Oleic acid coated Fe{sub 3}O{sub 4} (OA-Fe{sub 3}O{sub 4}) NPs were initially synthesized using a coprecipitation method. The as-synthesized OA-Fe{sub 3}O{sub 4} NPs were then used as seeds, on which the red upconversion luminescent shell (Mn{sup 2+}-doped NaYF{sub 4}:Yb/Er) was formed. Furthermore, hydrophobic to hydrophilic surface modification of the Fe{sub 3}O{sub 4}@Mn{sup 2+}-doped NaYF{sub 4}:Yb/Er NPs was achieved via a ligand exchange method where oleic acid was displaced by a PEG phosphate ligand [PEG = poly(ethylene glycol)]. These materials were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, and vibrating sample magnetometry (VSM). The Fe{sub 3}O{sub 4} cores were uniformly coated with a Mn{sup 2+}-doped NaYF{sub 4}:Yb

  10. Our interests in protein-protein interactions

    Indian Academy of Sciences (India)

    protein interactions. Evolution of P-P partnerships. Evolution of P-P structures. Evolutionary dynamics of P-P interactions. Dynamics of P-P interaction network. Host-pathogen interactions. CryoEM mapping of gigantic protein assemblies.

  11. Evolution of protein-protein interactions

    Indian Academy of Sciences (India)

    Evolution of protein-protein interactions · Our interests in protein-protein interactions · Slide 3 · Slide 4 · Slide 5 · Slide 6 · Slide 7 · Slide 8 · Slide 9 · Slide 10 · Slide 11 · Slide 12 · Slide 13 · Slide 14 · Slide 15 · Slide 16 · Slide 17 · Slide 18 · Slide 19 · Slide 20.

  12. 24-hour urine protein

    Science.gov (United States)

    Urine protein - 24 hour; Chronic kidney disease - urine protein; Kidney failure - urine protein ... Bladder tumor Heart failure High blood pressure during pregnancy ( preeclampsia ) Kidney disease caused by diabetes, high blood pressure, autoimmune disorders, ...

  13. Protein in diet

    Science.gov (United States)

    Diet - protein ... Protein foods are broken down into parts called amino acids during digestion. The human body needs a ... to eat animal products to get all the protein you need in your diet. Amino acids are ...

  14. Protein-losing enteropathy

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007338.htm Protein-losing enteropathy To use the sharing features on this page, please enable JavaScript. Protein-losing enteropathy is an abnormal loss of protein ...

  15. Nanotechnologies in protein microarrays.

    Science.gov (United States)

    Krizkova, Sona; Heger, Zbynek; Zalewska, Marta; Moulick, Amitava; Adam, Vojtech; Kizek, Rene

    2015-01-01

    Protein microarray technology became an important research tool for study and detection of proteins, protein-protein interactions and a number of other applications. The utilization of nanoparticle-based materials and nanotechnology-based techniques for immobilization allows us not only to extend the surface for biomolecule immobilization resulting in enhanced substrate binding properties, decreased background signals and enhanced reporter systems for more sensitive assays. Generally in contemporarily developed microarray systems, multiple nanotechnology-based techniques are combined. In this review, applications of nanoparticles and nanotech